@ohos.worker (Starting the Worker)

The Worker thread is an independent thread running in parallel with the main thread. The thread that creates the Worker thread is referred to as the host thread. The URL file passed in during worker creation is executed in the Worker thread. The Worker thread can process time-consuming operations, but cannot directly operate the UI.

With the Worker module, you can provide a multithreaded environment for an application, so that the application can perform a time-consuming operation in a background thread. This greatly prevents a computing-intensive or high-latency task from blocking the running of the host thread. A Worker instance will not be proactively destroyed once it is created. It consumes resources to keep running. Therefore, you should call the API to terminate it in a timely manner.

The Context object of the Worker thread is different from that of the UI main thread. The Worker thread does not support UI operations.

For details about the precautions for using Worker, see Precautions for Worker.

NOTE

The initial APIs of this module are supported since API version 7. Newly added APIs will be marked with a superscript to indicate their earliest API version.

Modules to Import

import { worker } from '@kit.ArkTS';

Attributes

System capability: SystemCapability.Utils.Lang

Name	Type	Readable	Writable	Description
workerPort9+	ThreadWorkerGlobalScope	Yes	Yes	Object of the Worker thread used to communicate with the host thread. Atomic service API: This API can be used in atomic services since API version 11.
parentPort(deprecated)	DedicatedWorkerGlobalScope	Yes	Yes	Object of the Worker thread used to communicate with the host thread. This attribute is supported since API version 7 and deprecated since API version 9. You are advised to use workerPort9+ instead.

WorkerOptions

Provides options that can be set for the Worker instance to create.

System capability: SystemCapability.Utils.Lang

Name	Type	Read-only	Optional	Description
type	‘classic’ |‘module’	Yes	Yes	Mode in which the Worker instance executes the script. The module type is not supported yet. The default value is classic. Atomic service API: This API can be used in atomic services since API version 11.
name	string	Yes	Yes	Name of the Worker thread. The default value is undefined. Atomic service API: This API can be used in atomic services since API version 11.
shared	boolean	Yes	Yes	Whether sharing of the Worker instance is enabled. Currently, sharing is not supported. Atomic service API: This API can be used in atomic services since API version 12.
priority18+	ThreadWorkerPriority	Yes	Yes	Priority of the Worker thread. Atomic service API: This API can be used in atomic services since API version 18.

ThreadWorkerPriority¹⁸⁺

Enumerates the priorities available for Worker threads. For details about the mappings between priorities and QoS levels, see QoS Level.

System capability: SystemCapability.Utils.Lang

Atomic service API: This API can be used in atomic services since API version 18.

Name	Value	Description
HIGH	0	High priority, corresponding to QOS_USER_INITIATED.
MEDIUM	1	Medium priority, corresponding to QOS_DEFAULT.
LOW	2	Low priority, corresponding to QOS_UTILITY.
IDLE	3	Background priority, corresponding to QOS_BACKGROUND.

ThreadWorker⁹⁺

Before using the following APIs, you must create a ThreadWorker instance. The ThreadWorker class inherits from WorkerEventTarget.

constructor⁹⁺

constructor(scriptURL: string, options?: WorkerOptions)

A constructor used to create a ThreadWorker instance.

Atomic service API: This API can be used in atomic services since API version 11.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
scriptURL	string	Yes	URL of the Worker thread file. For details about the rules, see Precautions for File URLs.
options	WorkerOptions	No	Options that can be set for the Worker instance.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200003	Worker initialization failed.
10200007	The worker file path is invalid.

Example

The following code snippet shows how to load the Worker thread file of the ability in the stage model. For details about how to use the library to load the Worker thread file, see Precautions for File URLs.

import { worker } from '@kit.ArkTS';

// Two scenarios are involved.

// Scenario 1: URL of the Worker thread file: "entry/src/main/ets/workers/worker.ets"
const workerStageModel01 = new worker.ThreadWorker('entry/ets/workers/worker.ets', {name:"first worker in Stage model"});

// Scenario 2: URL of the Worker thread file: "testworkers/src/main/ets/ThreadFile/workers/worker.ets"
const workerStageModel02 = new worker.ThreadWorker('testworkers/ets/ThreadFile/workers/worker.ets');

postMessage⁹⁺

postMessage(message: Object, transfer: ArrayBuffer[]): void

Sends a message from the host thread to the Worker thread by transferring object ownership.

System capability: SystemCapability.Utils.Lang

Atomic service API: This API can be used in atomic services since API version 11.

Parameters

Name	Type	Mandatory	Description
message	Object	Yes	Data to be sent to the Worker thread. The data object must be sequenceable. For details about the supported parameter types, see Sequenceable Data Types.
transfer	ArrayBuffer[]	Yes	ArrayBuffer instance holding an array of objects for which the ownership is transferred to the Worker thread. After the transfer, the objects are available only in the Worker thread. The array cannot be null.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200004	The Worker instance is not running.
10200006	An exception occurred during serialization.

Example

// Worker.ets
import { worker, MessageEvents, ErrorEvent } from '@kit.ArkTS';

// Create an object in the Worker thread for communicating with the host thread.
const workerPort = worker.workerPort

// The Worker thread receives information from the host thread.
workerPort.onmessage = (e: MessageEvents): void => {
  // data carries the information sent by the host thread.
  let data: number = e.data;
  // Write data to the received buffer.
  const view = new Int8Array(data).fill(3);
  // The Worker thread sends information to the host thread.
  workerPort.postMessage(view);
}

// Trigger a callback when an error occurs in the Worker thread.
workerPort.onerror = (err: ErrorEvent) => {
  console.log("worker.ets onerror" + err.message);
}

// Index.ets
import { worker, MessageEvents, ErrorEvent } from '@kit.ArkTS';

@Entry
@Component
struct Index {
  @State message: string = 'Hello World';

  build() {
    Row() {
      Column() {
        Text(this.message)
          .fontSize(50)
          .fontWeight(FontWeight.Bold)
          .onClick(() => {
            // Create a Worker instance in the host thread.
            const workerInstance = new worker.ThreadWorker("entry/ets/workers/Worker.ets");
            // The host thread transfers information to the Worker thread.
            const buffer = new ArrayBuffer(8);
            workerInstance.postMessage(buffer, [buffer]);
            // The host thread receives information from the Worker thread.
            workerInstance.onmessage = (e: MessageEvents): void => {
              // data carries the information sent by the Worker thread.
              let data: number = e.data;
              console.info("main thread data is  " + data);
              // Terminate the Worker instance.
              workerInstance.terminate();
            }
            // Call onexit().
            workerInstance.onexit = (code) => {
              console.log("main thread terminate");
            }

            workerInstance.onAllErrors = (err: ErrorEvent) => {
              console.log("main error message " + err.message);
            }
          })
      }
      .width('100%')
      .height('100%')
    }
  }
}

postMessage⁹⁺

postMessage(message: Object, options?: PostMessageOptions): void

Sends a message from the host thread to the Worker thread by transferring object ownership or copying data.

Atomic service API: This API can be used in atomic services since API version 11.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
message	Object	Yes	Data to be sent to the Worker thread. The data object must be sequenceable. For details about the supported parameter types, see Sequenceable Data Types.
options	PostMessageOptions	No	If this parameter is specified, it functions the same as ArrayBuffer[]. Specifically, the ownership of the objects in the array is transferred to the Worker thread and becomes unavailable in the host thread. The objects are available only in the Worker thread. If this parameter is not specified, the default value undefined is used, and information is transferred to the Worker thread by copying data.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200004	The Worker instance is not running.
10200006	An exception occurred during serialization.

Example

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");

workerInstance.postMessage("hello world");

let buffer = new ArrayBuffer(8);
workerInstance.postMessage(buffer, [buffer]);

postMessageWithSharedSendable¹²⁺

postMessageWithSharedSendable(message: Object, transfer?: ArrayBuffer[]): void

Sends a message from the host thread to the Worker thread. In the message, a sendable object is passed by reference, and a non-sendable object is passed by serialization.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
message	Object	Yes	Data to be sent to the Worker thread. The data object must be sequenceable or sendable. For details about the supported sequenceable types, see Sequenceable Data Types. For details about the supported sendable types, see Sendable Data Types.
transfer	ArrayBuffer[]	No	ArrayBuffer instance holding an array of objects for which the ownership is transferred to the Worker thread. After the transfer, the objects are available only in the Worker thread. The array cannot be null. The default value is an empty array.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200004	The Worker instance is not running.
10200006	An exception occurred during serialization.

Example

// index.ets
// Create a SendableObject instance and pass it to the Worker thread through the host thread.

import { worker } from '@kit.ArkTS';
import { SendableObject } from './sendable'

const workerInstance = new worker.ThreadWorker("entry/ets/workers/Worker.ets");
let object: SendableObject = new SendableObject();
workerInstance.postMessageWithSharedSendable(object);

// sendable.ets
// Define SendableObject.

@Sendable
export class SendableObject {
  a:number = 45;
}

// The worker file path is entry/src/main/ets/workers/Worker.ets.
// Worker.ets
// Receive and access the data passed from the host thread to the Worker thread.

import { SendableObject } from '../pages/sendable'
import { worker, ThreadWorkerGlobalScope, MessageEvents, ErrorEvent } from '@kit.ArkTS';

const workerPort: ThreadWorkerGlobalScope = worker.workerPort;
workerPort.onmessage = (e: MessageEvents) => {
  let obj: SendableObject = e.data;
  console.info("sendable obj is: " + obj.a);
}

on⁹⁺

on(type: string, listener: WorkerEventListener): void

Adds an event listener for the Worker thread. This API provides the same functionality as addEventListener⁹⁺.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Type of the event to listen for.
listener	WorkerEventListener	Yes	Callback to invoke when an event of the specified type occurs.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200004	Worker instance is not running.
10200005	The invoked API is not supported in workers.

Example

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
workerInstance.on("alert", ()=>{
    console.log("alert listener callback");
})

once⁹⁺

once(type: string, listener: WorkerEventListener): void

Adds an event listener for the Worker thread and removes the event listener after it is invoked once.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Type of the event to listen for.
listener	WorkerEventListener	Yes	Callback to invoke when an event of the specified type occurs.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200004	Worker instance is not running.
10200005	The invoked API is not supported in workers.

Example

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
workerInstance.once("alert", ()=>{
    console.log("alert listener callback");
})

off⁹⁺

off(type: string, listener?: WorkerEventListener): void

Removes an event listener for the Worker thread. This API provides the same functionality as removeEventListener⁹⁺.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Type of the event for which the event listener is to be removed.
listener	WorkerEventListener	No	Callback to invoke when the listener is removed.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200004	Worker instance is not running.
10200005	The invoked API is not supported in workers.

Example

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
// Use on, once, or addEventListener to add a listener for the "alert" event, and use off to remove the listener.
workerInstance.off("alert");

registerGlobalCallObject¹¹⁺

registerGlobalCallObject(instanceName: string, globalCallObject: Object): void

Registers an object with the ThreadWorker instance of the host thread. In this way, the methods of the object can be called in the Worker thread through callGlobalCallObjectMethod.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
instanceName	string	Yes	Key used for registration, based on which the registered object is identified during method calling.
globalCallObject	Object	Yes	Object to register. The ThreadWorker instance holds a strong reference to the object.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200004	Worker instance is not running.

Example

//Index.ets
const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
class TestObj {
  private message : string = "this is a message from TestObj"
  public getMessage() : string {
    return this.message;
  }
  public getMessageWithInput(str : string) : string {
    return this.message + " with input: " + str;
  }
}
let registerObj = new TestObj();
// Register registerObj with the ThreadWorker instance.
workerInstance.registerGlobalCallObject("myObj", registerObj);
workerInstance.postMessage("start worker")

// worker.ets
import { worker, MessageEvents } from '@kit.ArkTS';

const workerPort = worker.workerPort;
workerPort.onmessage = (e: MessageEvents): void => {
  try {
    // The method to call does not carry an input parameter.
    let res : string = workerPort.callGlobalCallObjectMethod("myObj", "getMessage", 0) as string;
    console.info("worker:", res) // worker: this is a message from TestObj
  } catch (error) {
    // Exception handling.
    console.error("worker: error code is " + error.code + " error message is " + error.message);
  }
  try {
    // The method to call carries input parameters.
    let res : string = workerPort.callGlobalCallObjectMethod("myObj", "getMessageWithInput", 0, "hello there!") as string;
    console.info("worker:", res) //worker: this is a message from TestObj with input: hello there!
  } catch (error) {
    // Exception handling.
    console.error("worker: error code is " + error.code + " error message is " + error.message);
  }
}

unregisterGlobalCallObject¹¹⁺

unregisterGlobalCallObject(instanceName?: string): void

Unregisters an object with the ThreadWorker instance of the host thread. This API releases the strong reference between the ThreadWorker instance and the target object. No error is reported if no object is matched.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
instanceName	string	No	Key used for registration. If this parameter is left blank, all registered objects registered in the ThreadWorker instance are unregistered.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200004	Worker instance is not running.

Example

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
class TestObj {
  private message : string = "this is a message from TestObj"
  public getMessage() : string {
    return this.message;
  }
  public getMessageWithInput(str : string) : string {
    return this.message + " with input: " + str;
  }
}
let registerObj = new TestObj();
workerInstance.registerGlobalCallObject("myObj", registerObj);
// Unregister the object.
workerInstance.unregisterGlobalCallObject("myObj");
// Unregister all objects from the ThreadWorker instance.
//workerInstance.unregisterGlobalCallObject();
workerInstance.postMessage("start worker")

terminate⁹⁺

terminate(): void

Terminates the Worker thread to stop it from receiving messages.

Atomic service API: This API can be used in atomic services since API version 11.

System capability: SystemCapability.Utils.Lang

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200004	The Worker instance is not running.

Example

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
workerInstance.terminate();

onexit⁹⁺

onexit?: (code: number) => void

Called when the Worker thread exits. The event handler is executed in the host thread. In the callback function, the code value is of the number type, where the value 1 indicates abnormal exit and 0 indicates normal exit.

Atomic service API: This API can be used in atomic services since API version 11.

System capability: SystemCapability.Utils.Lang

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1.Incorrect parameter types.
10200004	The Worker instance is not running.
10200005	The called API is not supported in the worker thread.

Example

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
workerInstance.onexit = (code) => {
 console.log("onexit");
}

// onexit is executed in either of the following ways:
// Main thread
workerInstance.terminate();

// Worker thread
//workerPort.close()

onerror⁹⁺

onerror?: (err: ErrorEvent) => void

Called when an exception occurs during worker execution. The event handler is executed in the host thread. In the callback function, the err type is ErrorEvent, indicating the received abnormal data.

Atomic service API: This API can be used in atomic services since API version 11.

System capability: SystemCapability.Utils.Lang

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1.Incorrect parameter types.
10200004	The Worker instance is not running.
10200005	The called API is not supported in the worker thread.

Example

import { worker, ErrorEvent } from '@kit.ArkTS';

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
workerInstance.onerror = (err: ErrorEvent) => {
  console.log("onerror" + err.message);
}

onAllErrors¹⁸⁺

onAllErrors?: ErrorCallback

Called when an exception occurs within the lifecycle of the Worker thread. The event handler is executed in the host thread.

onerror can capture only exceptions generated by synchronous methods within the onmessage callback. It cannot capture exceptions from multithreaded callbacks or modularization-related exceptions. Once an exception is captured, the Worker thread will proceed to the destruction process and cannot be used.

onAllErrors can capture global exceptions generated during the onmessage callback, timer callback, and file execution of the Worker thread. After an exception is captured by onAllErrors, the Worker thread remains alive and can continue to be used. You are advised to use onAllErrors instead of onerror.

Atomic service API: This API can be used in atomic services since API version 18.

System capability: SystemCapability.Utils.Lang

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200004	The Worker instance is not running.
10200005	The called API is not supported in the worker thread.

Example

import { worker, ErrorEvent } from '@kit.ArkTS';

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
workerInstance.onAllErrors = (err: ErrorEvent) => {
  console.log("onAllErrors" + err.message);
}

onmessage⁹⁺

onmessage?: (event: MessageEvents) => void

Called when the host thread receives a message sent by the Worker thread through workerPort.postMessage. The event handler is executed in the host thread. In the callback function, the event type is MessageEvents, indicating the received message data.

Atomic service API: This API can be used in atomic services since API version 11.

System capability: SystemCapability.Utils.Lang

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1.Incorrect parameter types.
10200004	The Worker instance is not running.
10200005	The called API is not supported in the worker thread.

Example

import { worker, MessageEvents } from '@kit.ArkTS';

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
workerInstance.onmessage = (e: MessageEvents): void => {
 // e: MessageEvents. The usage is as follows:
 // let data = e.data;
 console.log("onmessage");
}

onmessageerror⁹⁺

onmessageerror?: (event: MessageEvents) => void

Called when the Worker thread receives a message that cannot be serialized. The event handler is executed in the host thread. In the callback function, the event type is MessageEvents, indicating the received message data.

Atomic service API: This API can be used in atomic services since API version 11.

System capability: SystemCapability.Utils.Lang

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1.Incorrect parameter types.
10200004	The Worker instance is not running.
10200005	The called API is not supported in the worker thread.

Example

import { worker, MessageEvents } from '@kit.ArkTS';

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
workerInstance.onmessageerror = (err: MessageEvents) => {
  console.log("onmessageerror");
}

addEventListener⁹⁺

addEventListener(type: string, listener: WorkerEventListener): void

Adds an event listener for the Worker thread. This API provides the same functionality as on⁹⁺.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Type of the event to listen for.
listener	WorkerEventListener	Yes	Callback to invoke when an event of the specified type occurs.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200004	Worker instance is not running.
10200005	The invoked API is not supported in workers.

Example

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
workerInstance.addEventListener("alert", ()=>{
    console.log("alert listener callback");
})

removeEventListener⁹⁺

removeEventListener(type: string, callback?: WorkerEventListener): void

Removes an event listener for the Worker thread. This API provides the same functionality as off⁹⁺.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Type of the event for which the event listener is to be removed.
callback	WorkerEventListener	No	Callback to invoke when the listener is removed.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200004	Worker instance is not running.

Example

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
workerInstance.addEventListener("alert", ()=>{
    console.log("alert listener callback");
})
workerInstance.removeEventListener("alert");

dispatchEvent⁹⁺

dispatchEvent(event: Event): boolean

Dispatches the event defined for the Worker thread.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
event	Event	Yes	Event to dispatch.

Return value

Type	Description
boolean	Dispatch result. The value true means a successful dispatch, and false means the opposite.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200004	Worker instance is not running.

Example

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");

workerInstance.dispatchEvent({type:"eventType", timeStamp:0}); // timeStamp is not supported yet.

The dispatchEvent API can be used together with the on, once, and addEventListener APIs. The sample code is as follows:

import { worker, MessageEvents } from '@kit.ArkTS';

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");

// Usage 1:
workerInstance.on("alert_on", ()=>{
    console.log("alert listener callback");
})
workerInstance.once("alert_once", ()=>{
    console.log("alert listener callback");
})
workerInstance.addEventListener("alert_add", ()=>{
    console.log("alert listener callback");
})

// The event listener created by once is removed after being executed once.
workerInstance.dispatchEvent({type:"alert_once", timeStamp:0}); // timeStamp is not supported yet.
// The event listener created by on will not be proactively deleted.
workerInstance.dispatchEvent({type:"alert_on", timeStamp:0});
workerInstance.dispatchEvent({type:"alert_on", timeStamp:0});
// The event listener created by addEventListener will not be proactively deleted.
workerInstance.dispatchEvent({type:"alert_add", timeStamp:0});
workerInstance.dispatchEvent({type:"alert_add", timeStamp:0});

// Usage 2:
// The event type can be customized, and the special types "message", "messageerror", and "error" exist.
// When type = "message", the event handler defined by onmessage will also be executed.
// When type = "messageerror", the event handler defined by onmessageerror will also be executed.
// When type = "error", the event handler defined by onerror will also be executed.
// removeEventListener or off can be used to remove an event listener that is created by addEventListener, on, or once.

workerInstance.addEventListener("message", ()=>{
    console.log("message listener callback");
})
workerInstance.onmessage = (e: MessageEvents): void => {
    console.log("onmessage : message listener callback");
}
// When dispatchEvent is called to distribute the "message" event, the callback passed in addEventListener and onmessage will be invoked.
workerInstance.dispatchEvent({type:"message", timeStamp:0});

removeAllListener⁹⁺

removeAllListener(): void

Removes all event listeners for the Worker thread.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200004	Worker instance is not running.

Example

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
workerInstance.addEventListener("alert", ()=>{
    console.log("alert listener callback");
})
workerInstance.removeAllListener();

WorkerEventTarget⁹⁺

Processes worker listening events.

addEventListener⁹⁺

addEventListener(type: string, listener: WorkerEventListener): void

Adds an event listener for the Worker thread. This API provides the same functionality as on⁹⁺.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Type of the event to listen for.
listener	WorkerEventListener	Yes	Callback to invoke when an event of the specified type occurs.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200004	The Worker instance is not running.
10200005	The called API is not supported in the worker thread.

Example

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
workerInstance.addEventListener("alert", ()=>{
    console.log("alert listener callback");
})

removeEventListener⁹⁺

removeEventListener(type: string, callback?: WorkerEventListener): void

Removes an event listener for the Worker thread. This API provides the same functionality as off⁹⁺.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Type of the event for which the event listener is to be removed.
callback	WorkerEventListener	No	Callback to invoke when the listener is removed.

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200004	The Worker instance is not running.

Example

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
workerInstance.addEventListener("alert", ()=>{
    console.log("alert listener callback");
})
workerInstance.removeEventListener("alert");

dispatchEvent⁹⁺

dispatchEvent(event: Event): boolean

Dispatches the event defined for the Worker thread.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
event	Event	Yes	Event to dispatch.

Return value

Type	Description
boolean	Dispatch result. The value true means a successful dispatch, and false means the opposite.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200004	The Worker instance is not running.

Example

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");

workerInstance.dispatchEvent({type:"eventType", timeStamp:0}); // timeStamp is not supported yet.

The dispatchEvent API can be used together with the on, once, and addEventListener APIs. The sample code is as follows:

import { worker, MessageEvents } from '@kit.ArkTS';

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");

// Usage 1:
workerInstance.on("alert_on", ()=>{
    console.log("alert listener callback");
})
workerInstance.once("alert_once", ()=>{
    console.log("alert listener callback");
})
workerInstance.addEventListener("alert_add", ()=>{
    console.log("alert listener callback");
})

// The event listener created by once is removed after being executed once.
workerInstance.dispatchEvent({type:"alert_once", timeStamp:0}); // timeStamp is not supported yet.
// The event listener created by on will not be proactively deleted.
workerInstance.dispatchEvent({type:"alert_on", timeStamp:0});
workerInstance.dispatchEvent({type:"alert_on", timeStamp:0});
// The event listener created by addEventListener will not be proactively deleted.
workerInstance.dispatchEvent({type:"alert_add", timeStamp:0});
workerInstance.dispatchEvent({type:"alert_add", timeStamp:0});

// Usage 2:
// The event type can be customized, and the special types "message", "messageerror", and "error" exist.
// When type = "message", the event handler defined by onmessage will also be executed.
// When type = "messageerror", the event handler defined by onmessageerror will also be executed.
// When type = "error", the event handler defined by onerror will also be executed.
// removeEventListener or off can be used to remove an event listener that is created by addEventListener, on, or once.

workerInstance.addEventListener("message", ()=>{
    console.log("message listener callback");
})
workerInstance.onmessage = (e: MessageEvents): void => {
    console.log("onmessage : message listener callback");
}
// When dispatchEvent is called to distribute the "message" event, the callback passed in addEventListener and onmessage will be invoked.
workerInstance.dispatchEvent({type:"message", timeStamp:0});

removeAllListener⁹⁺

removeAllListener(): void

Removes all event listeners for the Worker thread.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200004	The Worker instance is not running.

Example

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
workerInstance.addEventListener("alert", ()=>{
    console.log("alert listener callback");
})
workerInstance.removeAllListener();

ThreadWorkerGlobalScope⁹⁺

Implements communication between the Worker thread and the host thread. The postMessage API is used to send messages to the host thread, and the close API is used to terminate the Worker thread. The ThreadWorkerGlobalScope class inherits from GlobalScope⁹⁺.

postMessage⁹⁺

postMessage(messageObject: Object, transfer: ArrayBuffer[]): void;

Sends a message from the Worker thread to the host thread by transferring object ownership.

Atomic service API: This API can be used in atomic services since API version 11.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
messageObject	Object	Yes	Data to be sent to the host thread. The data object must be sequenceable. For details about the supported parameter types, see Sequenceable Data Types.
transfer	ArrayBuffer[]	Yes	ArrayBuffer instance holding an array of objects for which the ownership is transferred to the host thread. After the transfer, the objects are available only in the host thread. The array cannot be null.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200004	The Worker instance is not running.
10200006	An exception occurred during serialization.

Example

// Main thread
import { worker, MessageEvents } from '@kit.ArkTS';

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
workerInstance.postMessage("hello world");
workerInstance.onmessage = (e: MessageEvents): void => {
    console.log("receive data from worker.ets");
}

// worker.ets
import { worker, MessageEvents } from '@kit.ArkTS';

const workerPort = worker.workerPort;
workerPort.onmessage = (e: MessageEvents): void => {
    let buffer = new ArrayBuffer(8);
    workerPort.postMessage(buffer, [buffer]);
}

postMessage⁹⁺

postMessage(messageObject: Object, options?: PostMessageOptions): void

Sends a message from the Worker thread to the host thread by transferring object ownership or copying data.

Atomic service API: This API can be used in atomic services since API version 11.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
messageObject	Object	Yes	Data to be sent to the host thread. The data object must be sequenceable. For details about the supported parameter types, see Sequenceable Data Types.
options	PostMessageOptions	No	If this parameter is specified, it functions the same as ArrayBuffer[]. Specifically, the ownership of the objects in the array is transferred to the host thread and becomes unavailable in the Worker thread. The objects are available only in the host thread. If this parameter is not specified, the default value undefined is used, and information is transferred to the host thread by copying data.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200004	The Worker instance is not running.
10200006	An exception occurred during serialization.

Example

// Main thread
import { worker, MessageEvents } from '@kit.ArkTS';

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
workerInstance.postMessage("hello world");
workerInstance.onmessage = (e: MessageEvents): void => {
    console.log("receive data from worker.ets");
}

// worker.ets
import { worker, MessageEvents } from '@kit.ArkTS';

const workerPort = worker.workerPort;
workerPort.onmessage = (e: MessageEvents): void => {
    workerPort.postMessage("receive data from main thread");
}

postMessageWithSharedSendable¹²⁺

postMessageWithSharedSendable(message: Object, transfer?: ArrayBuffer[]): void

Sends a message from the Worker thread to the host thread. In the message, a sendable object is passed by reference, and a non-sendable object is passed by serialization.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
message	Object	Yes	Data to be sent to the host thread. The data object must be sequenceable or sendable. For details about the supported sequenceable types, see Sequenceable Data Types. For details about the supported sendable types, see Sendable Data Types.
transfer	ArrayBuffer[]	No	ArrayBuffer instance holding an array of objects for which the ownership is transferred to the host thread. After the transfer, the objects are available only in the host thread. The array cannot be null. The default value is an empty array.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200004	The Worker instance is not running.
10200006	An exception occurred during serialization.

Example

// The worker file path is entry/src/main/ets/workers/Worker.ets.
// Worker.ets
// Create a SendableObject instance and pass it to the host thread through the Worker thread.

import { SendableObject } from '../pages/sendable'
import { worker, ThreadWorkerGlobalScope, MessageEvents, ErrorEvent } from '@kit.ArkTS';

const workerPort: ThreadWorkerGlobalScope = worker.workerPort;
workerPort.onmessage = (e: MessageEvents) => {
  let object: SendableObject = new SendableObject();
  workerPort.postMessageWithSharedSendable(object);
}

// sendable.ets
// Define SendableObject.

@Sendable
export class SendableObject {
  a:number = 45;
}

// Index.ets
// Receive the data passed from the Worker thread to the host thread and access its properties.

import { worker, MessageEvents } from '@kit.ArkTS';
import { SendableObject } from './sendable'

const workerInstance = new worker.ThreadWorker("entry/ets/workers/Worker.ets");
workerInstance.postMessage(1);
workerInstance.onmessage = (e: MessageEvents) => {
  let obj: SendableObject = e.data;
  console.info("sendable index obj is: " + obj.a);
}

callGlobalCallObjectMethod¹¹⁺

callGlobalCallObjectMethod(instanceName: string, methodName: string, timeout: number, …args: Object[]): Object

Calls a method of an object registered with the host thread. This API is called by the Worker thread. The invoking is synchronous for the Worker thread and asynchronous for the host thread. The return value is transferred through serialization.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
instanceName	string	Yes	Key used for registration. It is used to search for the object in the host thread.
methodName	string	Yes	Name of the method to call. Note that the method cannot be modified by async or generator, or return results asynchronously by using the asynchronous mechanism at the bottom layer. Otherwise, an exception is thrown.
timeout	number	Yes	Maximum duration that the current synchronous invoking waits, in ms. The value is an integer ranging from 1 to 5000. The value 0 means that the 5000 ms duration is used.
args	Object[]	No	Array of parameters in the method.

Return value

Type	Description
Object	Return value of the method in the host thread. The return value must be serializable. For details, see Sequenceable Data Types.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200004	Worker instance is not running.
10200006	An exception occurred during serialization.
10200019	The globalCallObject is not registered.
10200020	The method to be called is not callable or is an async method or a generator.
10200021	The global call exceeds the timeout.

Example

//Index.ets
const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
class TestObj {
  private message : string = "this is a message from TestObj"
  public getMessage() : string {
    return this.message;
  }
  public getMessageWithInput(str : string) : string {
    return this.message + " with input: " + str;
  }
}
let registerObj = new TestObj();
// Register registerObj with the ThreadWorker instance.
workerInstance.registerGlobalCallObject("myObj", registerObj);
workerInstance.postMessage("start worker")

// worker.ets
import { worker, MessageEvents } from '@kit.ArkTS';

const workerPort = worker.workerPort;
workerPort.onmessage = (e: MessageEvents): void => {
  try {
    // The method to call does not carry an input parameter.
    let res : string = workerPort.callGlobalCallObjectMethod("myObj", "getMessage", 0) as string;
    console.info("worker:", res) // worker: this is a message from TestObj
  } catch (error) {
    // Exception handling.
    console.error("worker: error code is " + error.code + " error message is " + error.message);
  }
  try {
    // The method to call carries input parameters.
    let res : string = workerPort.callGlobalCallObjectMethod("myObj", "getMessageWithInput", 0, "hello there!") as string;
    console.info("worker:", res) //worker: this is a message from TestObj with input: hello there!
  } catch (error) {
    // Exception handling.
    console.error("worker: error code is " + error.code + " error message is " + error.message);
  }
}

close⁹⁺

close(): void

Terminates the Worker thread to stop it from receiving messages.

Atomic service API: This API can be used in atomic services since API version 11.

System capability: SystemCapability.Utils.Lang

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200004	The Worker instance is not running.

Example

// Main thread
import { worker } from '@kit.ArkTS';

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");

// worker.ets
import { worker, MessageEvents } from '@kit.ArkTS';

const workerPort = worker.workerPort;
workerPort.onmessage = (e: MessageEvents): void => {
    workerPort.close()
}

onmessage⁹⁺

onmessage?: (this: ThreadWorkerGlobalScope, ev: MessageEvents) => void

Called when the Worker thread receives a message sent by the host thread through postMessage. The event handler is executed in the Worker thread. In the callback function, this indicates the caller’s ThreadWorkerGlobalScope, and the ev type is MessageEvents, indicating the received message data.

Atomic service API: This API can be used in atomic services since API version 11.

System capability: SystemCapability.Utils.Lang

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Incorrect parameter types.
10200004	The Worker instance is not running.
10200005	The called API is not supported in the worker thread.

Example

// Main thread
import { worker } from '@kit.ArkTS';

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
workerInstance.postMessage("hello world");

// worker.ets
import { worker, MessageEvents } from '@kit.ArkTS';

const workerPort = worker.workerPort;
workerPort.onmessage = (e: MessageEvents): void => {
    console.log("receive main thread message");
}

onmessageerror⁹⁺

onmessageerror?: (this: ThreadWorkerGlobalScope, ev: MessageEvents) => void

Called when the Worker thread receives a message that cannot be deserialized. The event handler is executed in the Worker thread. In the callback function, this indicates the caller’s ThreadWorkerGlobalScope, and the ev type is MessageEvents, indicating the received message data.

Atomic service API: This API can be used in atomic services since API version 11.

System capability: SystemCapability.Utils.Lang

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Incorrect parameter types.
10200004	The Worker instance is not running.
10200005	The called API is not supported in the worker thread.

Example

// Main thread
import { worker } from '@kit.ArkTS';

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");

// worker.ets
import { worker, MessageEvents } from '@kit.ArkTS';

const workerPort = worker.workerPort;
workerPort.onmessageerror = (err: MessageEvents) => {
    console.log("worker.ets onmessageerror");
}

WorkerEventListener⁹⁺

Implements event listening.

(event: Event)⁹⁺

(event: Event): void|Promise<void>

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
event	Event	Yes	Event class for the callback to invoke.

Return value

Type	Description
void | Promise<void>	Returns no value or returns a Promise.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200004	Worker instance is not running.
10200005	The invoked API is not supported in workers.

Example

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets");
workerInstance.addEventListener("alert", ()=>{
    console.log("alert listener callback");
})

GlobalScope⁹⁺

Implements the running environment of the Worker thread. The GlobalScope class inherits from WorkerEventTarget.

Attributes

Atomic service API: This API can be used in atomic services since API version 11.

System capability: SystemCapability.Utils.Lang

Name	Type	Readable	Writable	Description
name	string	Yes	No	Worker instance specified when there is a new Worker instance.
self	GlobalScope & typeof globalThis	Yes	No	GlobalScope itself.

onerror⁹⁺

onerror?: (ev: ErrorEvent) => void

Called when an exception occurs during worker execution. The event handler is executed in the Worker thread. In the callback function, the ev type is ErrorEvent, indicating the received abnormal data.

Atomic service API: This API can be used in atomic services since API version 11.

System capability: SystemCapability.Utils.Lang

Example

// Main thread
import { worker } from '@kit.ArkTS';

const workerInstance = new worker.ThreadWorker("entry/ets/workers/worker.ets")

// worker.ets
import { worker, ErrorEvent } from '@kit.ArkTS';

const workerPort = worker.workerPort
workerPort.onerror = (err: ErrorEvent) => {
    console.log("worker.ets onerror" + err.message)
}

MessageEvents⁹⁺

Holds the data transferred between Worker threads.

Atomic service API: This API can be used in atomic services since API version 11.

System capability: SystemCapability.Utils.Lang

Name	Type	Readable	Writable	Description
data	any	Yes	No	Data transferred between threads.

MessageType⁷⁺

type MessageType = ‘message’|‘messageerror’;

Defines the message type.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Type	Description
‘message’	The message type is message, fixed at ‘message’.
‘messageerror’	The message type is messageerror, fixed at ‘messageerror’.

ErrorCallback¹⁸⁺

type ErrorCallback = (err: ErrorEvent) => void

Defines an error callback.

Atomic service API: This API can be used in atomic services since API version 18.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
err	ErrorEvent	Yes	Error event class, which provides detailed information about the exception occurred during Worker execution.

Worker^(deprecated)

Before using the following APIs, you must create a Worker instance. The Worker class inherits from EventTarget.

NOTE

This API is supported since API version 7 and deprecated since API version 9. You are advised to use ThreadWorker⁹⁺ instead.

constructor^(deprecated)

constructor(scriptURL: string, options?: WorkerOptions)

A constructor used to create a Worker instance.

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use ThreadWorker.constructor⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
scriptURL	string	Yes	URL of the Worker thread file. For details about the rules, see Precautions for File URLs.
options	WorkerOptions	No	Options that can be set for the Worker instance.

Example

The following code snippet shows how to load the Worker thread file of the ability in the stage model. For details about how to use the library to load the Worker thread file, see Precautions for File URLs.

import { worker } from '@kit.ArkTS';

// Two scenarios are involved.

// Scenario 1: URL of the Worker thread file: "entry/src/main/ets/workers/worker.ets"
const workerStageModel01 = new worker.ThreadWorker('entry/ets/workers/worker.ets', {name:"first worker in Stage model"});

// Scenario 2: URL of the Worker thread file: "testworkers/src/main/ets/ThreadFile/workers/worker.ets"
const workerStageModel02 = new worker.ThreadWorker('testworkers/ets/ThreadFile/workers/worker.ets');

postMessage^(deprecated)

postMessage(message: Object, transfer: ArrayBuffer[]): void

Sends a message from the host thread to the Worker thread by transferring object ownership.

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use ThreadWorker.postMessage⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
message	Object	Yes	Data to be sent to the Worker thread. The data object must be sequenceable. For details about the supported parameter types, see Sequenceable Data Types.
transfer	ArrayBuffer[]	Yes	ArrayBuffer instance holding an array of objects for which the ownership is transferred to the Worker thread. After the transfer, the objects are available only in the Worker thread. The array cannot be null.

Example

const workerInstance = new worker.Worker("workers/worker.ets");

let buffer = new ArrayBuffer(8);
workerInstance.postMessage(buffer, [buffer]);

postMessage^(deprecated)

postMessage(message: Object, options?: PostMessageOptions): void

Sends a message from the host thread to the Worker thread by transferring object ownership or copying data.

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use ThreadWorker.postMessage⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
message	Object	Yes	Data to be sent to the Worker thread. The data object must be sequenceable. For details about the supported parameter types, see Sequenceable Data Types.
options	PostMessageOptions	No	If this parameter is specified, it functions the same as ArrayBuffer[]. Specifically, the ownership of the objects in the array is transferred to the Worker thread and becomes unavailable in the host thread. The objects are available only in the Worker thread. If this parameter is not specified, the default value undefined is used, and information is transferred to the Worker thread by copying data.

Example

const workerInstance = new worker.Worker("workers/worker.ets");

workerInstance.postMessage("hello world");

let buffer = new ArrayBuffer(8);
workerInstance.postMessage(buffer, [buffer]);

on^(deprecated)

on(type: string, listener: EventListener): void

Adds an event listener for the Worker thread. This API provides the same functionality as addEventListener^(deprecated).

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use ThreadWorker.on⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Type of the event to listen for.
listener	EventListener	Yes	Callback to invoke when an event of the specified type occurs.

Example

const workerInstance = new worker.Worker("workers/worker.ets");
workerInstance.on("alert", ()=>{
    console.log("alert listener callback");
})

once^(deprecated)

once(type: string, listener: EventListener): void

Adds an event listener for the Worker thread and removes the event listener after it is invoked once.

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use ThreadWorker.once⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Type of the event to listen for.
listener	EventListener	Yes	Callback to invoke when an event of the specified type occurs.

Example

const workerInstance = new worker.Worker("workers/worker.ets");
workerInstance.once("alert", ()=>{
    console.log("alert listener callback");
})

off^(deprecated)

off(type: string, listener?: EventListener): void

Removes an event listener for the Worker thread. This API provides the same functionality as removeEventListener^(deprecated).

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use ThreadWorker.off⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Type of the event for which the event listener is to be removed.
listener	EventListener	No	Callback to invoke when the listener is removed.

Example

const workerInstance = new worker.Worker("workers/worker.ets");
// Use on, once, or addEventListener to add a listener for the "alert" event, and use off to remove the listener.
workerInstance.off("alert");

terminate^(deprecated)

terminate(): void

Terminates the Worker thread to stop it from receiving messages.

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use ThreadWorker.terminate⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Example

const workerInstance = new worker.Worker("workers/worker.ets");
workerInstance.terminate();

onexit^(deprecated)

onexit?: (code: number) => void

Called when the Worker thread exits. The event handler is executed in the host thread. In the callback function, the code value is of the number type, where the value 1 indicates abnormal exit and 0 indicates normal exit.

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use ThreadWorker.onexit⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Example

const workerInstance = new worker.Worker("workers/worker.ets");
workerInstance.onexit = (code) => {
    console.log("onexit");
}

// onexit is executed in either of the following ways:
// Main thread
workerInstance.terminate();

// Worker thread
//parentPort.close()

onerror^(deprecated)

onerror?: (err: ErrorEvent) => void

Called when an exception occurs during worker execution. The event handler is executed in the host thread. In the callback function, the err type is ErrorEvent, indicating the received abnormal data.

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use ThreadWorker.onerror⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Example

import { worker, ErrorEvent } from '@kit.ArkTS';

const workerInstance = new worker.Worker("workers/worker.ets");
workerInstance.onerror = (err: ErrorEvent) => {
  console.log("onerror" + err.message);
}

onmessage^(deprecated)

onmessage?: (event: MessageEvent) => void

Called when the host thread receives a message sent by the Worker thread through workerPort.postMessage. The event handler is executed in the host thread. In the callback function, the event type is MessageEvent, indicating the received message data.

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use ThreadWorker.onmessage⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Example

import { worker } from '@kit.ArkTS';

const workerInstance = new worker.Worker("workers/worker.ets");
workerInstance.onmessage = (): void => {
    console.log("onmessage");
}

onmessageerror^(deprecated)

onmessageerror?: (event: MessageEvent) => void

Called when the Worker thread receives a message that cannot be serialized. The event handler is executed in the host thread. In the callback function, the event type is MessageEvent, indicating the received message data.

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use ThreadWorker.onmessageerror⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Example

import { worker } from '@kit.ArkTS';

const workerInstance = new worker.Worker("workers/worker.ets");
workerInstance.onmessageerror = (err) => {
    console.log("onmessageerror");
}

EventTarget^(deprecated)

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use WorkerEventTarget⁹⁺ instead.

addEventListener^(deprecated)

addEventListener(type: string, listener: EventListener): void

Adds an event listener for the Worker thread. This API provides the same functionality as on^(deprecated).

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use addEventListener⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Type of the event to listen for.
listener	EventListener	Yes	Callback to invoke when an event of the specified type occurs.

Example

// worker.ets
import { DedicatedWorkerGlobalScope, ErrorEvent, MessageEvents, worker } from '@kit.ArkTS';

const workerPort: DedicatedWorkerGlobalScope = worker.parentPort;

workerPort.addEventListener("alert", () => {
  console.info("alert listener callback");
})

removeEventListener^(deprecated)

removeEventListener(type: string, callback?: EventListener): void

Removes an event listener for the Worker thread. This API provides the same functionality as off^(deprecated).

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use removeEventListener⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Type of the event for which the event listener is to be removed.
callback	EventListener	No	Callback to invoke when the listener is removed.

Example

// worker.ets
import { DedicatedWorkerGlobalScope, ErrorEvent, MessageEvents, worker } from '@kit.ArkTS';

const workerPort: DedicatedWorkerGlobalScope = worker.parentPort;

workerPort.addEventListener("alert", () => {
  console.info("alert listener callback");
})

workerPort.removeEventListener('alert');

dispatchEvent^(deprecated)

dispatchEvent(event: Event): boolean

Dispatches the event defined for the Worker thread.

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use dispatchEvent⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
event	Event	Yes	Event to dispatch.

Return value

Type	Description
boolean	Dispatch result. The value true means a successful dispatch, and false means the opposite.

Example

// worker.ets
import { DedicatedWorkerGlobalScope, ErrorEvent, MessageEvents, worker } from '@kit.ArkTS';

const workerPort: DedicatedWorkerGlobalScope = worker.parentPort;

workerPort.addEventListener("alert_add", ()=>{
  console.info("alert listener callback");
})

workerPort.dispatchEvent({type: 'alert_add', timeStamp: 0}); // timeStamp is not supported yet.

The dispatchEvent API can be used together with the addEventListener API. The sample code is as follows:

// Main thread
import { worker } from '@kit.ArkTS';

const workerInstance = new worker.Worker("workers/worker.ets");
workerInstance.postMessage("hello world");
workerInstance.onmessage = (): void => {
    console.info("receive data from worker.ets");
}

// worker.ets
import { DedicatedWorkerGlobalScope, ErrorEvent, MessageEvents, worker } from '@kit.ArkTS';

const workerPort: DedicatedWorkerGlobalScope = worker.parentPort;

workerPort.addEventListener("alert", ()=>{
  console.info("alert listener callback");
})

workerPort.onmessage = (event: MessageEvents) => {
  workerPort.dispatchEvent({type:"alert", timeStamp:0}); // timeStamp is not supported yet.
}

removeAllListener^(deprecated)

removeAllListener(): void

Removes all event listeners for the Worker thread.

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use removeAllListener⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Example

// worker.ets
import { DedicatedWorkerGlobalScope, ErrorEvent, MessageEvents, worker } from '@kit.ArkTS';

const workerPort: DedicatedWorkerGlobalScope = worker.parentPort;

workerPort.addEventListener("alert_add", ()=>{
  console.info("alert listener callback");
})

workerPort.removeAllListener();

DedicatedWorkerGlobalScope^(deprecated)

Implements communication between the Worker thread and the host thread. The postMessage API is used to send messages to the host thread, and the close API is used to terminate the Worker thread. This class inherits from WorkerGlobalScope.

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use ThreadWorkerGlobalScope⁹⁺ instead.

postMessage^(deprecated)

postMessage(messageObject: Object, transfer: Transferable[]): void

Sends a message from the Worker thread to the host thread by transferring object ownership.

NOTE
This API is deprecated since API version 9. You are advised to use ThreadWorkerGlobalScope⁹⁺.postMessage⁹⁺.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
messageObject	Object	Yes	Data to be sent to the host thread. The data object must be sequenceable. For details about the supported parameter types, see Sequenceable Data Types.
transfer	Transferable[]	Yes	Currently, this parameter is not supported.

postMessage⁹⁺

postMessage(messageObject: Object, transfer: ArrayBuffer[]): void

Sends a message from the Worker thread to the host thread by transferring object ownership.

NOTE

The DedicatedWorkerGlobalScope class is deprecated since API version 9. You are advised to use ThreadWorkerGlobalScope⁹⁺.postMessage⁹⁺.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
messageObject	Object	Yes	Data to be sent to the host thread. The data object must be sequenceable. For details about the supported parameter types, see Sequenceable Data Types.
transfer	ArrayBuffer[]	Yes	ArrayBuffer instance holding an array of objects for which the ownership is transferred to the host thread. After the transfer, the objects are available only in the host thread. The array cannot be null.

Example

// Main thread
import { worker } from '@kit.ArkTS';

const workerInstance = new worker.Worker("workers/worker.ets");
workerInstance.postMessage("hello world");
workerInstance.onmessage = (): void => {
    // let data = e.data;
    console.log("receive data from worker.ets");
}

// worker.ets
import { worker } from '@kit.ArkTS';

const workerPort = worker.workerPort;
workerPort.onmessage = (): void => {
    // let data = e.data;
    let buffer = new ArrayBuffer(5)
    workerPort.postMessage(buffer, [buffer]);
}

postMessage^(deprecated)

postMessage(messageObject: Object, options?: PostMessageOptions): void

Sends a message from the Worker thread to the host thread by transferring object ownership or copying data.

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use ThreadWorkerGlobalScope⁹⁺.postMessage⁹⁺.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
messageObject	Object	Yes	Data to be sent to the host thread. The data object must be sequenceable. For details about the supported parameter types, see Sequenceable Data Types.
options	PostMessageOptions	No	If this parameter is specified, it functions the same as ArrayBuffer[]. Specifically, the ownership of the objects in the array is transferred to the host thread and becomes unavailable in the Worker thread. The objects are available only in the host thread. If this parameter is not specified, the default value undefined is used, and information is transferred to the host thread by copying data.

Example

// Main thread
import { worker } from '@kit.ArkTS';

const workerInstance = new worker.Worker("entry/ets/workers/worker.ets");
workerInstance.postMessage("hello world");
workerInstance.onmessage = (): void => {
    console.log("receive data from worker.ets");
}

// worker.ets
import { ErrorEvent, MessageEvents, worker } from '@kit.ArkTS';

const parentPort = worker.parentPort;
parentPort.onmessage = (e: MessageEvents) => {
  parentPort.postMessage("receive data from main thread");
}

close^(deprecated)

close(): void

Terminates the Worker thread to stop it from receiving messages.

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use ThreadWorkerGlobalScope⁹⁺.close⁹⁺.

System capability: SystemCapability.Utils.Lang

Example

// Main thread
import { worker } from '@kit.ArkTS';

const workerInstance = new worker.Worker("workers/worker.ets");

// worker.ets
import { worker } from '@kit.ArkTS';

const parentPort = worker.parentPort;
parentPort.onmessage = (): void => {
    parentPort.close()
}

onmessage^(deprecated)

onmessage?: (this: DedicatedWorkerGlobalScope, ev: MessageEvent) => void

Called when the Worker thread receives a message sent by the host thread through postMessage. The event handler is executed in the Worker thread. In the callback function, this indicates the caller’s DedicatedWorkerGlobalScope, and the ev type is MessageEvent, indicating the received message data.

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use ThreadWorkerGlobalScope⁹⁺.onmessage⁹⁺.

System capability: SystemCapability.Utils.Lang

Example

// Main thread
import { worker } from '@kit.ArkTS';

const workerInstance = new worker.Worker("workers/worker.ets");
workerInstance.postMessage("hello world");

// worker.ets
import { worker } from '@kit.ArkTS';

const parentPort = worker.parentPort;
parentPort.onmessage = (): void => {
    console.log("receive main thread message");
}

onmessageerror^(deprecated)

onmessageerror?: (this: DedicatedWorkerGlobalScope, ev: MessageEvent) => void

Called when the Worker thread receives a message that cannot be deserialized. The event handler is executed in the Worker thread. In the callback function, this indicates the caller’s DedicatedWorkerGlobalScope, and the ev type is MessageEvent, indicating the received message data.

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use ThreadWorkerGlobalScope⁹⁺.onmessageerror⁹⁺.

System capability: SystemCapability.Utils.Lang

Example

// Main thread
import { worker } from '@kit.ArkTS';

const workerInstance = new worker.Worker("workers/worker.ets");

// worker.ets
import { worker } from '@kit.ArkTS';

const parentPort = worker.parentPort;
parentPort.onmessageerror = () => {
    console.log("worker.ets onmessageerror")
}

PostMessageOptions

Defines the object for which the ownership is to be transferred during data transfer. The object must be an ArrayBuffer instance. After the ownership is transferred, the object becomes unavailable in the sender and can be used only in the receiver.

Atomic service API: This API can be used in atomic services since API version 11.

System capability: SystemCapability.Utils.Lang

Name	Type	Readable	Writable	Description
transfer	Object[]	Yes	Yes	ArrayBuffer array used to transfer the ownership. The array cannot be null.

Event

Defines the event.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Name	Type	Readable	Writable	Description
type	string	Yes	No	Type of the event.
timeStamp	number	Yes	No	Timestamp (accurate to millisecond) when the event is created. This parameter is not supported yet.

EventListener^(deprecated)

Implements event listening.

NOTE

This API is supported since API version 7 and deprecated since API version 9. You are advised to use WorkerEventListener⁹⁺ instead.

(evt: Event)^(deprecated)

(evt: Event): void|Promise<void>

NOTE

This API is supported since API version 7 and deprecated since API version 9. You are advised to use (event:Event)⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
evt	Event	Yes	Event class for the callback to invoke.

Return value

Type	Description
void | Promise<void>	Returns no value or returns a Promise.

Example

const workerInstance = new worker.Worker("workers/worker.ets");
workerInstance.addEventListener("alert", ()=>{
    console.log("alert listener callback");
})

ErrorEvent

Provides detailed information about the exception that occurs during worker execution. The ErrorEvent class inherits from Event.

Atomic service API: This API can be used in atomic services since API version 11.

System capability: SystemCapability.Utils.Lang

Name	Type	Readable	Writable	Description
message	string	Yes	No	Information about the exception.
filename	string	Yes	No	File where the exception is located.
lineno	number	Yes	No	Serial number of the line where the exception is located.
colno	number	Yes	No	Serial number of the column where the exception is located.
error	Object	Yes	No	Type of the exception.

MessageEvent<T>

Holds the data transferred between Worker threads.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Name	Type	Readable	Writable	Description
data	T	Yes	No	Data transferred between threads.

WorkerGlobalScope^(deprecated)

Implements the running environment of the Worker thread. The WorkerGlobalScope class inherits from EventTarget.

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use GlobalScope⁹⁺ instead.

Attributes

System capability: SystemCapability.Utils.Lang

Name	Type	Readable	Writable	Description
name	string	Yes	No	Worker instance specified when there is a new Worker instance.
self	WorkerGlobalScope & typeof globalThis	Yes	No	WorkerGlobalScope.

onerror^(deprecated)

onerror?: (ev: ErrorEvent) =&gt; void

Called when an exception occurs during worker execution. The event handler is executed in the Worker thread. In the callback function, the ev type is ErrorEvent, indicating the received abnormal data.

NOTE
This API is supported since API version 7 and deprecated since API version 9. You are advised to use GlobalScope⁹⁺.onerror⁹⁺.

System capability: SystemCapability.Utils.Lang

Example

// Main thread
import { worker } from '@kit.ArkTS';

const workerInstance = new worker.Worker("workers/worker.ets")

// worker.ets
import { worker, ErrorEvent } from '@kit.ArkTS';

const parentPort = worker.parentPort
parentPort.onerror = (err: ErrorEvent) => {
    console.log("worker.ets onerror" + err.message)
}

More Information

Sequenceable Data Types

The following object types are supported: basic types except Symbol, Date, String, RegExp, Array, Map, Set, Object (simple objects only, for example, objects created using {} or new Object), ArrayBuffer, and TypedArray. (Note that only attributes can be transferred for common objects. Prototypes and methods cannot be transferred.)

Exception: When an object created through a custom class is passed, no serialization error occurs. However, the attributes (such as Function) of the custom class cannot be passed through serialization. > NOTE
> An FA project of API version 9 is used as an example.

// Main thread
import { worker, MessageEvents } from '@kit.ArkTS';

const workerInstance = new worker.ThreadWorker("workers/worker.ets");
workerInstance.postMessage("message from main thread to worker");
workerInstance.onmessage = (d: MessageEvents): void => {
  // When the Worker thread passes obj2, data contains obj2, excluding the Init or SetName method.
  let data: string  = d.data;
}

// worker.ets
import { worker, MessageEvents, ErrorEvent } from '@kit.ArkTS';

const workerPort = worker.workerPort;
class MyModel {
    name = "undefined"
    Init() {
        this.name = "MyModel"
    }
}
workerPort.onmessage = (d: MessageEvents): void => {
  console.log("worker.ets onmessage");
  let data: string = d.data;
  let func1 = () => {
    console.log("post message is function");
  }
  // workerPort.postMessage(func1); A serialization error occurs when passing func1.
  let obj2 = new MyModel();
  workerPort.postMessage(obj2);     // No serialization error occurs when passing obj2.
}
workerPort.onmessageerror = () => {
    console.log("worker.ets onmessageerror");
}
workerPort.onerror = (err: ErrorEvent) => {
    console.log("worker.ets onerror" + err.message);
}

Memory Model

The Worker thread is implemented based on the actor model. In the Worker interaction process, the JS host thread can create multiple Worker threads, each of which are isolated and transfer data through serialization. They complete computing tasks and return the result to the host thread.

Each actor concurrently processes tasks of the host thread. For each actor, there is a message queue and a single-thread execution module. The message queue receives requests from the host thread and other actors; the single-thread execution module serially processes requests, sends requests to other actors, and creates new actors. These isolated actors use the asynchronous mode and can run concurrently.

Sample Code

NOTE

Only the FA model is supported in API version 8 and earlier versions. If you want to use API version 8 or earlier, change the API for constructing the Worker instance and the API for creating an object in the Worker thread for communicating with the host thread.

FA Model

The following uses API version 9 as an example.

// Main thread (The following assumes that the workers directory and pages directory are at the same level.)
import { worker, MessageEvents, ErrorEvent } from '@kit.ArkTS';

// Create a Worker instance in the host thread.
const workerInstance = new worker.ThreadWorker("workers/worker.ets");

// The host thread transfers information to the Worker thread.
const buffer = new ArrayBuffer(8);
workerInstance.postMessage(buffer, [buffer]);

// The host thread receives information from the Worker thread.
workerInstance.onmessage = (e: MessageEvents): void => {
    // data carries the information sent by the Worker thread.
    let data: string = e.data;
    console.log("main thread onmessage");

    // Terminate the Worker instance.
    workerInstance.terminate();
}

// Call onexit().
workerInstance.onexit = (code) => {
    console.log("main thread terminate");
}

workerInstance.onerror = (err: ErrorEvent) => {
    console.log("main error message " + err.message);
}

// worker.ets
import { worker, MessageEvents, ErrorEvent } from '@kit.ArkTS';

// Create an object in the Worker thread for communicating with the host thread.
const workerPort = worker.workerPort

// The Worker thread receives information from the host thread.
workerPort.onmessage = (e: MessageEvents): void => {
    // data carries the information sent by the host thread.
    let data: number = e.data;
    const view = new Int8Array(data).fill(3);
    console.log("worker.ets onmessage");

    // The Worker thread sends information to the host thread.
    workerPort.postMessage(view);
}

// Trigger a callback when an error occurs in the Worker thread.
workerPort.onerror = (err: ErrorEvent) => {
    console.log("worker.ets onerror");
}

Add the following configuration to the module-level entry/build-profile.json5 file:

  "buildOption": {
    "sourceOption": {
      "workers": [
        "./src/main/ets/entryability/workers/worker.ets"
      ]
    }
  }

Stage Model

The following uses API version 18 as an example.

// Index.ets
import { worker, MessageEvents, ErrorEvent } from '@kit.ArkTS';

@Entry
@Component
struct Index {
  @State message: string = 'Hello World';
  build() {
    Row() {
      Column() {
        Text(this.message)
          .fontSize(50)
          .fontWeight(FontWeight.Bold)
          .onClick(() => {
            // Create a Worker instance in the host thread.
            const workerInstance = new worker.ThreadWorker("entry/ets/workers/Worker.ets");
            // The host thread transfers information to the Worker thread.
            const buffer = new ArrayBuffer(8);
            workerInstance.postMessage(buffer);
            // The host thread receives information from the Worker thread.
            workerInstance.onmessage = (e: MessageEvents): void => {
              // data carries the information sent by the Worker thread.
              let data: number = e.data;
              console.info("main thread data is  " + data);
              // Terminate the Worker instance.
              workerInstance.terminate();
            }
            // Call onexit().
            workerInstance.onexit = (code) => {
              console.log("main thread terminate");
            }

            workerInstance.onAllErrors = (err: ErrorEvent) => {
              console.log("main error message " + err.message);
            }
          })
      }
      .width('100%')
      .height('100%')
    }
  }
}

// Worker.ets
import { worker, MessageEvents, ErrorEvent } from '@kit.ArkTS';

// Create an object in the Worker thread for communicating with the host thread.
const workerPort = worker.workerPort

// The Worker thread receives information from the host thread.
workerPort.onmessage = (e: MessageEvents): void => {
  // data carries the information sent by the host thread.
  let data: number = e.data;
  // Write data to the received buffer.
  const view = new Int8Array(data).fill(3);
  // The Worker thread sends information to the host thread.
  workerPort.postMessage(view);
}

// Trigger a callback when an error occurs in the Worker thread.
workerPort.onerror = (err: ErrorEvent) => {
  console.log("worker.ets onerror" + err.message);
}

Add the following configuration to the module-level entry/build-profile.json5 file:

  "buildOption": {
    "sourceOption": {
      "workers": [
        "./src/main/ets/workers/Worker.ets"
      ]
    }
  }

你可能感兴趣的鸿蒙文章

harmony 鸿蒙ArkTS

harmony 鸿蒙Compilation Toolchain Error Codes

harmony 鸿蒙TypeScript Compiler Error Codes

harmony 鸿蒙Utils Error Codes

harmony 鸿蒙js-apis-arkts-collections

harmony 鸿蒙@arkts.math.Decimal (High-Precision Math Library Decimal)

harmony 鸿蒙@arkts.lang (ArkTS Base Capability)

harmony 鸿蒙@arkts.utils (ArkTS Utils)

harmony 鸿蒙@ohos.util.ArrayList (Linear Container ArrayList)

harmony 鸿蒙@ohos.buffer (Buffer)