Working with Arrays Using JSVM-API

Introduction

JSVM-API provides APIs for directly managing JavaScript (JS) arrays.

Basic Concepts

JSVM-API can be used to create, access, modify, and traverse arrays. Before using JSVM-API to work with arrays, it’s helpful if you understand the following concepts:

• Array creation: You can use OH_JSVM_CreateArray to create an array and pass it to the JS layer.
• Array-related operations: You can use the APIs provides by the JSVM module to obtain the length of a JS array, retrieve the element at the specified index, and set the element value at the specified index.
• TypedArray: A TypedArray object in JS is an array-like view of an underlying binary data buffer. It can be simply understood as an array of elements of the specified type. There is no constructor for TypedArray objects, but its child class constructor can be used to construct TypedArray data. The child classes of TypedArray include Int8Array, Uint8Array, Uint8ClampedArray, Int16Array, and Int32Array.
• ArrayBuffer: ArrayBuffer is a data struct used to represent a binary data buffer of fixed length.
• DataView: DataView is a JS view that allows a variety of number types to be read and written in an ArrayBuffer object.

Available APIs

Example

If you are just starting out with JSVM-API, see JSVM-API Development Process. The following demonstrates only the C++ code involved in array development.

OH_JSVM_CreateArray

Use OH_JSVM_CreateArray to create a JS array object.

CPP code:

// hello.cpp
#include "napi/native_api.h"
#include "ark_runtime/jsvm.h"
#include <hilog/log.h>
// Register the CreateArray callback.
static int DIFF_VALUE_FIVE = 5;
// Define OH_JSVM_CreateArray. 
static JSVM_Value CreateArray(JSVM_Env env, JSVM_CallbackInfo info)
{
    // Create an empty array.
    JSVM_Value array = nullptr;
    JSVM_Status status = OH_JSVM_CreateArray(env, &array);
    // Assign values to the created array.
    for (int i = 0; i < DIFF_VALUE_FIVE; i++) {
        JSVM_Value element;
        OH_JSVM_CreateInt32(env, i, &element);
        OH_JSVM_SetElement(env, array, i, element);
    }
    if (status != JSVM_OK) {
        OH_LOG_ERROR(LOG_APP, "JSVM CreateArray fail");
    } else {
        OH_LOG_INFO(LOG_APP, "JSVM CreateArray success");
    }
    return array;
}
static JSVM_CallbackStruct param[] = {
    {.data = nullptr, .callback = CreateArray},
};
static JSVM_CallbackStruct *method = param;
// Set a property descriptor named createArray and associate it with a callback. This allows the CreateArray callback to be called from JS.
static JSVM_PropertyDescriptor descriptor[] = {
    {"createArray", nullptr, method++, nullptr, nullptr, nullptr, JSVM_DEFAULT},
};
// Call the C++ code from JS.
const char *srcCallNative = R"JS(
  function testCreateArray() {
    return createArray();
  }
  testCreateArray();
)JS";

Expected result:

JSVM CreateArray success

OH_JSVM_CreateArrayWithLength

Use OH_JSVM_CreateArrayWithLength to create a JS array object of the specified length.

CPP code:

// hello.cpp
#include "napi/native_api.h"
#include "ark_runtime/jsvm.h"
#include <hilog/log.h>
// Define OH_JSVM_CreateArrayWithLength.
static JSVM_Value CreateArrayWithLength(JSVM_Env env, JSVM_CallbackInfo info)
{
    size_t argc = 1;
    JSVM_Value argv[1] = {nullptr};
    JSVM_Value result = nullptr;
    // Obtain the callback information.
    OH_JSVM_GetCbInfo(env, info, &argc, argv, nullptr, nullptr);
    // Obtain the array length passed.
    int32_t length;
    OH_JSVM_GetValueInt32(env, argv[0], &length);
    // Call OH_JSVM_CreateArrayWithLength to create an array with the specified length.
    JSVM_Status status = OH_JSVM_CreateArrayWithLength(env, length, &result);
    if (status == JSVM_OK) {
        // Set an element in the created array.
        for (int32_t i = 0; i < length; i++) {
            JSVM_Value value;
            OH_JSVM_CreateInt32(env, i, &value);
            OH_JSVM_SetElement(env, result, i, value);
        }
        OH_LOG_INFO(LOG_APP, "JSVM CreateArrayWithLength success");
    } else {
        OH_LOG_ERROR(LOG_APP, "JSVM CreateArrayWithLength fail");
    }
    return result;
}
// Register the CreateArrayWithLength callback.
static JSVM_CallbackStruct param[] = {
    {.data = nullptr, .callback = CreateArrayWithLength},
};
static JSVM_CallbackStruct *method = param;
// Set a property descriptor named createArrayWithLength and associate it with a callback. This allows the CreateArrayWithLength callback to be called from JS.
static JSVM_PropertyDescriptor descriptor[] = {
    {"createArrayWithLength", nullptr, method++, nullptr, nullptr, nullptr, JSVM_DEFAULT},
};
// Call the C++ code from JS.
const char *srcCallNative = R"JS(
let num = 7;
function testCreateArrayWithLength(num){
    return createArrayWithLength(num);
}
testCreateArrayWithLength(num);
)JS";

Expected result:

JSVM CreateArrayWithLength success

OH_JSVM_CreateTypedarray

Use OH_JSVM_CreateTypedarray to create a JS TypedArray object based on an ArrayBuffer. The TypedArray object provides an array-like view over an underlying data buffer, where each element has the same underlying binary scalar data type.

CPP code:

// hello.cpp
#include "napi/native_api.h"
#include "ark_runtime/jsvm.h"
#include <hilog/log.h>
// Define OH_JSVM_CreateTypedarray.
static int DIFF_VALUE_THREE = 3;
static JSVM_Value CreateTypedArray(JSVM_Env env, JSVM_CallbackInfo info)
{
    size_t argc = 1;
    JSVM_Value args[1] = {nullptr};
    OH_JSVM_GetCbInfo(env, info, &argc, args, nullptr, nullptr);
    int32_t typeNum;
    OH_JSVM_GetValueInt32(env, args[0], &typeNum);
    JSVM_TypedarrayType arrayType;
    // Set the element size.
    size_t elementSize = 0;
    // Convert the value to the JSVM_TypedarrayType type.
    arrayType = static_cast<JSVM_TypedarrayType>(typeNum);
    switch (typeNum) {
    case JSVM_INT8_ARRAY:
    case JSVM_UINT8_ARRAY:
    case JSVM_UINT8_CLAMPED_ARRAY:
        elementSize = sizeof(int8_t);
        break;
    case JSVM_INT16_ARRAY:
    case JSVM_UINT16_ARRAY:
        elementSize = sizeof(int16_t);
        break;
    case JSVM_INT32_ARRAY:
    case JSVM_UINT32_ARRAY:
        elementSize = sizeof(int32_t);
        break;
    case JSVM_FLOAT32_ARRAY:
        elementSize = sizeof(float);
        break;
    case JSVM_FLOAT64_ARRAY:
        elementSize = sizeof(double);
        break;
    case JSVM_BIGINT64_ARRAY:
    case JSVM_BIGUINT64_ARRAY:
        elementSize = sizeof(int64_t);
        break;
    default:
        // By default, an array of the JSVM_INT8_ARRAY type is created.
        arrayType = JSVM_INT8_ARRAY;
        elementSize = sizeof(int8_t);
        break;
    }
    size_t length = DIFF_VALUE_THREE;
    JSVM_Value arrayBuffer = nullptr;
    JSVM_Value typedArray = nullptr;
    void *data;
    // Create an ArrayBuffer object.
    OH_JSVM_CreateArraybuffer(env, length * elementSize, (void **)&data, &arrayBuffer);
    // Create a TypedArray object of the specified type.
    JSVM_Status status = OH_JSVM_CreateTypedarray(env, arrayType, length, arrayBuffer, 0, &typedArray);
    if (status != JSVM_OK) {
        OH_LOG_ERROR(LOG_APP, "JSVM CreateTypedArray fail");
    } else {
        OH_LOG_INFO(LOG_APP, "JSVM CreateTypedArray success");
    }
    return typedArray;
}
// Register the CreateTypedArray callback.
static JSVM_CallbackStruct param[] = {
    {.data = nullptr, .callback = CreateTypedArray},
};
static JSVM_CallbackStruct *method = param;
// Set a property descriptor named createTypedArray and associate it with a callback. This allows the CreateTypedArray callback to be called from JS.
static JSVM_PropertyDescriptor descriptor[] = {
    {"createTypedArray", nullptr, method++, nullptr, nullptr, nullptr, JSVM_DEFAULT},
};
// Call the C++ code from JS.
const char *srcCallNative = R"JS(
const type = {
    INT8_ARRAY: 0,
    UINT8_ARRAY: 1,
    UINT8_CLAMPED_ARRAY: 2,
    INT16_ARRAY: 3,
    UINT16_ARRAY: 4,
    INT32_ARRAY: 5,
    UINT32_ARRAY: 6,
    FLOAT32_ARRAY: 7,
    FLOAT64_ARRAY: 8,
    BIGINT64_ARRAY: 9,
    BIGUINT64_ARRAY: 10
};
createTypedArray(type.INT8_ARRAY);
createTypedArray(type.INT32_ARRAY);
)JS";

Expected result:

JSVM CreateTypedArray success
JSVM CreateTypedArray success

OH_JSVM_CreateDataview

Use OH_JSVM_CreateDataview to create a JS DataView object based on an ArrayBuffer. The DataView object provides an array-like view over an underlying data buffer.

CPP code:

static int DIFF_VALUE_FOUR = 4;
static int DIFF_VALUE_TWELVE = 12;
// Define OH_JSVM_CreateDataview.
static JSVM_Value CreateDataView(JSVM_Env env, JSVM_CallbackInfo info)
{
    // Obtain the two parameters passed from JS.
    size_t argc = 2;
    JSVM_Value args[2] = {nullptr};
    JSVM_Value arrayBuffer = nullptr;
    JSVM_Value result = nullptr;
    // Byte length of DataView.
    size_t byteLength = DIFF_VALUE_TWELVE;
    // Offset of the byte.
    size_t byteOffset = DIFF_VALUE_FOUR;
    // Obtain the parameters of the callback.
    OH_JSVM_GetCbInfo(env, info, &argc, args, nullptr, nullptr);
    // Convert the parameter into the object type.
    OH_JSVM_CoerceToObject(env, args[0], &arrayBuffer);
    // Create a DataView object with the specified byte length and offset.
    JSVM_Status status = OH_JSVM_CreateDataview(env, byteLength, arrayBuffer, byteOffset, &result);
    // Obtain the pointer to the DataView object and the length.
    uint8_t *data = nullptr;
    size_t length = 0;
    // Assign values to DataView.
    for (size_t i = 0; i < length; i++) {
        data[i] = static_cast<uint8_t>(i + 1);
    }
    int32_t infoType;
    OH_JSVM_GetValueInt32(env, args[1], &infoType);
    size_t returnLength;
    JSVM_Value returnArrayBuffer = nullptr;
    size_t returnOffset;
    enum InfoType { BYTE_LENGTHE, ARRAY_BUFFERE, BYTE_OFFSET };
    // Obtain DataView information.
    OH_JSVM_GetDataviewInfo(env, result, &returnLength, (void **)&data, &returnArrayBuffer, &returnOffset);
    JSVM_Value returnResult = nullptr;
    switch (infoType) {
    case BYTE_LENGTHE:
        JSVM_Value len;
        OH_JSVM_CreateInt32(env, returnLength, &len);
        returnResult = len;
        if (status != JSVM_OK) {
            OH_LOG_ERROR(LOG_APP, "JSVM CreateDataView fail");
        } else {
            OH_LOG_INFO(LOG_APP, "JSVM CreateDataView success, returnLength: %{public}d", returnLength);
        }
        break;
    case ARRAY_BUFFERE:
        bool isArraybuffer;
        OH_JSVM_IsArraybuffer(env, returnArrayBuffer, &isArraybuffer);
        JSVM_Value isArray;
        OH_JSVM_GetBoolean(env, isArraybuffer, &isArray);
        returnResult = isArray;
        if (status != JSVM_OK) {
            OH_LOG_ERROR(LOG_APP, "JSVM CreateDataView fail");
        } else {
            OH_LOG_INFO(LOG_APP, "JSVM CreateDataView success, isArraybuffer: %{public}d", isArraybuffer);
        }
        break;
    case BYTE_OFFSET:
        JSVM_Value offset;
        OH_JSVM_CreateInt32(env, returnOffset, &offset);
        returnResult = offset;
        if (status != JSVM_OK) {
            OH_LOG_ERROR(LOG_APP, "JSVM CreateDataView fail");
        } else {
            OH_LOG_INFO(LOG_APP, "JSVM CreateDataView success, returnOffset: %{public}d", returnOffset);
        }
        break;
    default:
        break;
    }
    return returnResult;
}
// Register the CreateDataView callback.
static JSVM_CallbackStruct param[] = {
    {.data = nullptr, .callback = CreateDataView},
};
static JSVM_CallbackStruct *method = param;
// Set a property descriptor named createDataView and associate it with a callback. This allows the CreateDataView callback to be called from JS.
static JSVM_PropertyDescriptor descriptor[] = {
    {"createDataView", nullptr, method++, nullptr, nullptr, nullptr, JSVM_DEFAULT},
};
// Call the C++ code from JS.
const char *srcCallNative = R"JS(
 let BYTE_LENGTH = 0;
 createDataView(new ArrayBuffer(16), BYTE_LENGTH);
 let IS_ARRAYBUFFER = 1;
 createDataView(new ArrayBuffer(16), IS_ARRAYBUFFER);
 let BYTE_OFFSET = 2;
 createDataView(new ArrayBuffer(16), BYTE_OFFSET);
)JS";

Expected result:

CreateDataView success, returnLength: 12
JSVM CreateDataView success, isArraybuffer: 1
JSVM CreateDataView success, returnOffset: 4

OH_JSVM_GetArrayLength

Use OH_JSVM_GetArrayLength to obtain the length of an array.

CPP code:

// hello.cpp
#include "napi/native_api.h"
#include "ark_runtime/jsvm.h"
#include <hilog/log.h>
// Define OH_JSVM_GetArrayLength.
static JSVM_Value GetArrayLength(JSVM_Env env, JSVM_CallbackInfo info)
{
    size_t argc = 1;
    JSVM_Value args[1] = {nullptr};
    JSVM_Value result = nullptr;
    // Initialize length.
    uint32_t length = 0;
    OH_JSVM_GetCbInfo(env, info, &argc, args, nullptr, nullptr);
    // Check whether the parameter is an array.
    bool isArray = false;
    OH_JSVM_IsArray(env, args[0], &isArray);
    if (!isArray) {
        OH_LOG_INFO(LOG_APP, "JSVM Argument must be an array");
        return nullptr;
    }
    /*
     * If the array length is successfully obtained, length is assigned to the actual JSArray length, and the API returns the JSVM_OK status code.
     * If args[0] is not of the JSArray type, for example, args[0] is a proxy object, the length cannot be obtained.
     * In this case, length remains unchanged, and the JSVM_ARRAY_EXPECTED status code is returned.
     */
    JSVM_Status status = OH_JSVM_GetArrayLength(env, args[0], &length);
    if (status == JSVM_OK) {
        // Create a return value.
        OH_JSVM_CreateInt32(env, length, &result);
        OH_LOG_INFO(LOG_APP, "JSVM length: %{public}d", length);
    }
    return result;
}
// Register the GetArrayLength callback.
static JSVM_CallbackStruct param[] = {
    {.data = nullptr, .callback = GetArrayLength},
};
static JSVM_CallbackStruct *method = param;
// Set a property descriptor named getArrayLength and associate it with a callback. This allows the GetArrayLength callback to be called from JS.
static JSVM_PropertyDescriptor descriptor[] = {
    {"getArrayLength", nullptr, method++, nullptr, nullptr, nullptr, JSVM_DEFAULT},
};
// Call the C++ code from JS.
const char *srcCallNative = R"JS(
let data = [0, 1, 2, 3, 4, 5];
getArrayLength(data);
)JS";

Expected result:

JSVM length: 6

OH_JSVM_GetTypedarrayInfo

Use OH_JSVM_GetTypedarrayInfo to obtain information about a TypedArray object.

CPP code:

// hello.cpp
#include "napi/native_api.h"
#include "ark_runtime/jsvm.h"
#include <hilog/log.h>
// Define OH_JSVM_GetTypedarrayInfo.
static JSVM_Value GetTypedArrayInfo(JSVM_Env env, JSVM_CallbackInfo info)
{
    // Obtain and parse the parameters passed to a JS callback within a JSVM. The first parameter is the TypedArray type of the information to obtain, and the second parameter is the enums of the information type to obtain.
    size_t argc = 2;
    JSVM_Value args[2] = {nullptr};
    OH_JSVM_GetCbInfo(env, info, &argc, args, nullptr, nullptr);

    // Convert the second parameter to the int32 type for comparison.
    int32_t infoTypeParam;
    OH_JSVM_GetValueInt32(env, args[1], &infoTypeParam);
    // Define the infoType enums in the same sequence as those in ArkTS.
    enum InfoType { INFO_TYPE, INFO_LENGTH, INFO_ARRAY_BUFFER, INFO_BYTE_OFFSET };
    void *data;
    JSVM_TypedarrayType type;
    size_t byteOffset, length;
    JSVM_Value arrayBuffer = nullptr;
    // Call OH_JSVM_GetTypedarrayInfo to obtain TypedArray information.
    JSVM_Status status = OH_JSVM_GetTypedarrayInfo(env, args[0], &type, &length, &data, &arrayBuffer, &byteOffset);
    JSVM_Value result = nullptr;
    // Return the property value based on the property name.
    switch (infoTypeParam) {
    case INFO_TYPE:
        // If the input parameter is TypedArray data of the int8 type, the value type is JSVM_INT8_ARRAY.
        JSVM_Value int8_type;
        OH_JSVM_GetBoolean(env, type == JSVM_INT8_ARRAY, &int8_type);
        result = int8_type;
        if (status != JSVM_OK) {
            OH_LOG_ERROR(LOG_APP, "JSVM GetTypedArrayInfo fail");
        } else {
            OH_LOG_INFO(LOG_APP, "JSVM GetTypedArrayInfo success, JSVM_INT8_ARRAY: %{public}d", type == JSVM_INT8_ARRAY);
        }
        break;
    case INFO_LENGTH:
        // Number of elements in the TypedArray object.
        JSVM_Value jsvmLength;
        OH_JSVM_CreateInt32(env, length, &jsvmLength);
        result = jsvmLength;
        if (status != JSVM_OK) {
            OH_LOG_ERROR(LOG_APP, "JSVM GetTypedArrayInfo fail");
        } else {
            OH_LOG_INFO(LOG_APP, "JSVM GetTypedArrayInfo success, length: %{public}d", length);
        }
        break;
    case INFO_BYTE_OFFSET:
        // Byte offset of the first TypedArray element in the native array.
        JSVM_Value jsvmOffset;
        OH_JSVM_CreateInt32(env, byteOffset, &jsvmOffset);
        result = jsvmOffset;
        if (status != JSVM_OK) {
            OH_LOG_ERROR(LOG_APP, "JSVM GetTypedArrayInfo fail");
        } else {
            OH_LOG_INFO(LOG_APP, "JSVM GetTypedArrayInfo success, byteOffset: %{public}d", byteOffset);
        }
        break;
    case INFO_ARRAY_BUFFER:
        // ArrayBuffer under TypedArray.
        bool isArrayBuffer;
        OH_JSVM_IsArraybuffer(env, arrayBuffer, &isArrayBuffer);
        JSVM_Value isArray;
        OH_JSVM_GetBoolean(env, isArrayBuffer, &isArray);
        result = isArray;
        if (status != JSVM_OK) {
            OH_LOG_ERROR(LOG_APP, "JSVM GetTypedArrayInfo fail");
        } else {
            OH_LOG_INFO(LOG_APP, "JSVM GetTypedArrayInfo success, isArrayBuffer: %{public}d", isArrayBuffer);
        }
        break;
    default:
        break;
    }
    return result;
}
// Register the GetTypedArrayInfo callback.
static JSVM_CallbackStruct param[] = {
    {.data = nullptr, .callback = GetTypedArrayInfo},
};
static JSVM_CallbackStruct *method = param;
// Set a property descriptor named getTypedArrayInfo and associate it with a callback. This allows the GetTypedArrayInfo callback to be called from JS.
static JSVM_PropertyDescriptor descriptor[] = {
    {"getTypedArrayInfo", nullptr, method++, nullptr, nullptr, nullptr, JSVM_DEFAULT},
};
// Call the C++ code from JS.
const char *srcCallNative = R"JS(
// is JSVM_INT8_ARRAY
getTypedArrayInfo(new Int8Array(3), 0);
// Length
getTypedArrayInfo(new Int8Array(5), 1);
// is_arraybuffer
getTypedArrayInfo(new Int8Array(5), 2);
// Byte offset.
getTypedArrayInfo(new Int8Array(1), 3);
)JS";

Expected result:

JSVM GetTypedArrayInfo success, JSVM_INT8_ARRAY: 1
JSVM GetTypedArrayInfo success, length: 5
JSVM GetTypedArrayInfo success, isArrayBuffer: 1
JSVM GetTypedArrayInfo success, byteOffset: 0

OH_JSVM_GetDataviewInfo

Use OH_JSVM_GetDataviewInfo to obtain information about a DataView object.

CPP code:

// hello.cpp
#include "napi/native_api.h"
#include "ark_runtime/jsvm.h"
#include <hilog/log.h>
// Define OH_JSVM_GetDataviewInfo.
static JSVM_Value GetDataViewInfo(JSVM_Env env, JSVM_CallbackInfo info)
{
    // Obtain and parse the parameters passed to a JS callback within a JSVM. The first parameter is the DataView type of the information to obtain, and the second parameter is the enums of the information type to obtain.
    size_t argc = 2;
    JSVM_Value args[2] = {nullptr};
    OH_JSVM_GetCbInfo(env, info, &argc, args, nullptr, nullptr);
    // Convert the second parameter to an int32 number.
    int32_t infoType;
    OH_JSVM_GetValueInt32(env, args[1], &infoType);
    size_t byteLength;
    void *data;
    JSVM_Value arrayBuffer = nullptr;
    size_t byteOffset;
    // Define the infoType enums in the same sequence as those in ArkTS.
    enum infoTypeEnum { BYTE_LENGTHE, ARRAY_BUFFERE, BYTE_OFFSET };
    // Obtain DataView information.
    JSVM_Status status = OH_JSVM_GetDataviewInfo(env, args[0], &byteLength, &data, &arrayBuffer, &byteOffset);
    JSVM_Value result = nullptr;
    switch (infoType) {
    case BYTE_LENGTHE:
        // Return the length of DataView.
        JSVM_Value len;
        OH_JSVM_CreateInt32(env, byteLength, &len);
        result = len;
        if (status != JSVM_OK) {
            OH_LOG_ERROR(LOG_APP, "JSVM GetDataViewInfo fail");
        } else {
            OH_LOG_INFO(LOG_APP, "JSVM GetDataViewInfo success, byteLength: %{public}d", byteLength);
        }
        break;
    case ARRAY_BUFFERE:
        // Check whether data in Info of DataView is an ArrayBuffer object.
        bool isArrayBuffer;
        OH_JSVM_IsArraybuffer(env, arrayBuffer, &isArrayBuffer);
        JSVM_Value isArray;
        OH_JSVM_GetBoolean(env, isArrayBuffer, &isArray);
        result = isArray;
        if (status != JSVM_OK) {
            OH_LOG_ERROR(LOG_APP, "JSVM GetDataViewInfo fail");
        } else {
            OH_LOG_INFO(LOG_APP, "JSVM GetDataViewInfo success, isArrayBuffer: %{public}d", isArrayBuffer);
        }
        break;
    case BYTE_OFFSET:
        // Return the offset of DataView.
        JSVM_Value offset;
        OH_JSVM_CreateInt32(env, byteOffset, &offset);
        result = offset;
        if (status != JSVM_OK) {
            OH_LOG_ERROR(LOG_APP, "JSVM GetDataViewInfo fail");
        } else {
            OH_LOG_INFO(LOG_APP, "JSVM GetDataViewInfo success, byteOffset: %{public}d", byteOffset);
        }
        break;
    default:
        break;
    }
    return result;
}
// Register the GetDataViewInfo callback.
static JSVM_CallbackStruct param[] = {
    {.data = nullptr, .callback = GetDataViewInfo},
};
static JSVM_CallbackStruct *method = param;
// Set a property descriptor named getDataViewInfo and associate it with a callback. This allows the GetDataViewInfo callback to be called from JS.
static JSVM_PropertyDescriptor descriptor[] = {
    {"getDataViewInfo", nullptr, method++, nullptr, nullptr, nullptr, JSVM_DEFAULT},
};
// Call the C++ code from JS.
const char *srcCallNative = R"JS(
// Byte length.
getDataViewInfo(new DataView(new Int8Array([2,5]).buffer), 0);
// Check whether the data is an ArrayBuffer object.
let data = 'a';
let isarraybuffer = 1;
getDataViewInfo(data, isarraybuffer);
// Check whether the data is an ArrayBuffer object.
data = new DataView(new Int8Array([2,5,3]).buffer);
isarraybuffer = 1;
getDataViewInfo(data, isarraybuffer);
// byte_offset
data = new DataView(new Int8Array([2,5,3]).buffer);
isarraybuffer = 2;
getDataViewInfo(data, isarraybuffer);
)JS";

Expected result:

JSVM GetDataViewInfo success, byteLength: 2
JSVM GetDataViewInfo fail
JSVM GetDataViewInfo success, isArrayBuffer: 1
JSVM GetDataViewInfo success, byteOffset: 0

OH_JSVM_IsArray

Use OH_JSVM_IsArray to check whether a JS object is an array.

CPP code:

// hello.cpp
#include "napi/native_api.h"
#include "ark_runtime/jsvm.h"
#include <hilog/log.h>
// Define OH_JSVM_IsArray.
static JSVM_Value IsArray(JSVM_Env env, JSVM_CallbackInfo info)
{
    size_t argc = 1;
    JSVM_Value args[1] = {nullptr};
    OH_JSVM_GetCbInfo(env, info, &argc, args, nullptr, nullptr);
    bool result = false;
    JSVM_Status status = OH_JSVM_IsArray(env, args[0], &result);
    JSVM_Value returnValue = nullptr;
    OH_JSVM_GetBoolean(env, result, &returnValue);
    if (status != JSVM_OK) {
        OH_LOG_ERROR(LOG_APP, "JSVM IsArray fail");
    } else {
        OH_LOG_INFO(LOG_APP, "JSVM IsArray success, IsArray: %{public}d", result);
    }
    return returnValue;
}
// Register the IsArray callback.
static JSVM_CallbackStruct param[] = {
    {.data = nullptr, .callback = IsArray},
};
static JSVM_CallbackStruct *method = param;
// Set a property descriptor named isArray and associate it with a callback. This allows the IsArray callback to be called from JS.
static JSVM_PropertyDescriptor descriptor[] = {
    {"isArray", nullptr, method++, nullptr, nullptr, nullptr, JSVM_DEFAULT},
};
// Call the C++ code from JS.
const char *srcCallNative = R"JS(
let data = [1, 2, 3, 4, 5];
isArray(data);
)JS";

Expected result:

JSVM IsArray success, IsArray: 1

OH_JSVM_SetElement

Use OH_JSVM_SetElement to set an element at the specified index for a JS object.

CPP code:

// hello.cpp
#include "napi/native_api.h"
#include "ark_runtime/jsvm.h"
#include <hilog/log.h>
// Define OH_JSVM_SetElement.
static int DIFF_VALUE_THREE = 3;
static JSVM_Value SetElement(JSVM_Env env, JSVM_CallbackInfo info) {
    size_t argc = DIFF_VALUE_THREE;
    JSVM_Value args[3] = {nullptr};
    OH_JSVM_GetCbInfo(env, info, &argc, args, nullptr, nullptr);
    int32_t index = 0;
    OH_JSVM_GetValueInt32(env, args[1], &index);
    JSVM_Status status = OH_JSVM_SetElement(env, args[0], index, args[2]);
    if (status != JSVM_OK) {
        OH_LOG_ERROR(LOG_APP, "JSVM SetElement fail");
    } else {
        OH_LOG_INFO(LOG_APP, "JSVM SetElement success");
    }
    return args[0];
}
// Register the SetElement callback.
static JSVM_CallbackStruct param[] = {
    {.data = nullptr, .callback = SetElement},
};
static JSVM_CallbackStruct *method = param;
// Set a property descriptor named setElement and associate it with a callback. This allows the SetElement callback to be called from JS.
static JSVM_PropertyDescriptor descriptor[] = {
    {"setElement", nullptr, method++, nullptr, nullptr, nullptr, JSVM_DEFAULT},
};
// Call the C++ code from JS.
const char *srcCallNative = R"JS(
setElement(3);
)JS";

Expected result:

JSVM SetElement success

OH_JSVM_GetElement

Use OH_JSVM_GetElement to obtain the element at the specified index of a JS object.

CPP code:

// hello.cpp
#include "napi/native_api.h"
#include "ark_runtime/jsvm.h"
#include <hilog/log.h>
// Define OH_JSVM_GetElement.
static JSVM_Value GetElement(JSVM_Env env, JSVM_CallbackInfo info) {
    // Obtain the two parameters passed from JS.
    size_t argc = 2;
    JSVM_Value args[2] = {nullptr};
    OH_JSVM_GetCbInfo(env, info, &argc, args, nullptr, nullptr);
    // Obtain the index value of the element.
    uint32_t index;
    OH_JSVM_GetValueUint32(env, args[1], &index);
    // Obtain the element value at the index and store it in result.
    JSVM_Value result = nullptr;
    JSVM_Status status = OH_JSVM_GetElement(env, args[0], index, &result);
    if (status != JSVM_OK) {
        OH_LOG_ERROR(LOG_APP, "JSVM GetElement fail");
    } else {
        OH_LOG_INFO(LOG_APP, "JSVM GetElement success");
    }
    return result;
}
// Register the GetElement callback.
static JSVM_CallbackStruct param[] = {
    {.data = nullptr, .callback = GetElement},
};
static JSVM_CallbackStruct *method = param;
// Set a property descriptor named getElement and associate it with a callback. This allows the GetElement callback to be called from JS.
static JSVM_PropertyDescriptor descriptor[] = {
    {"getElement", nullptr, method++, nullptr, nullptr, nullptr, JSVM_DEFAULT},
};
// Call the C++ code from JS.
const char *srcCallNative = R"JS(
let arr = [10, 'hello', null, true];
getElement(arr, 3);
)JS";

Expected result:

JSVM GetElement success

OH_JSVM_HasElement

Use OH_JSVM_HasElement to check whether a JS object has an element at the specified index.

CPP code:

// hello.cpp
#include "napi/native_api.h"
#include "ark_runtime/jsvm.h"
#include <hilog/log.h>
// Define OH_JSVM_HasElement.
static JSVM_Value HasElement(JSVM_Env env, JSVM_CallbackInfo info)
{
    // Obtain the two parameters passed from JS.
    size_t argc = 2;
    JSVM_Value args[2] = {nullptr};
    OH_JSVM_GetCbInfo(env, info, &argc, args, nullptr, nullptr);
    // Obtain the index of the element to be checked.
    uint32_t index;
    OH_JSVM_GetValueUint32(env, args[1], &index);
    // Check whether the element exists based on the given index.
    bool hasElement = true;
    JSVM_Status status = OH_JSVM_HasElement(env, args[0], index, &hasElement);
    // Convert the boolean value to JSVM_Value and return it.
    JSVM_Value result = nullptr;
    OH_JSVM_GetBoolean(env, hasElement, &result);
    if (status != JSVM_OK) {
        OH_LOG_ERROR(LOG_APP, "JSVM hasElement fail");
    } else {
        OH_LOG_INFO(LOG_APP, "JSVM hasElement: %{public}d", hasElement);
    }
    return result;
}
// Register the HasElement callback.
static JSVM_CallbackStruct param[] = {
    {.data = nullptr, .callback = HasElement},
};
static JSVM_CallbackStruct *method = param;
// Set a property descriptor named hasElement and associate it with a callback. This allows the HasElement callback to be called from JS.
static JSVM_PropertyDescriptor descriptor[] = {
    {"hasElement", nullptr, method++, nullptr, nullptr, nullptr, JSVM_DEFAULT},
};
// Call the C++ code from JS.
const char *srcCallNative = R"JS(
let arr = [10, 'hello', null, true];
hasElement(arr, 0);
hasElement(arr, 4);
)JS";

Expected result:

JSVM hasElement: 1
JSVM hasElement: 0

OH_JSVM_DeleteElement

Use OH_JSVM_DeleteElement to delete the element at the specified index from a JS object.

CPP code:

// hello.cpp
#include "napi/native_api.h"
#include "ark_runtime/jsvm.h"
#include <hilog/log.h>
// Define OH_JSVM_DeleteElement.
static JSVM_Value DeleteElement(JSVM_Env env, JSVM_CallbackInfo info) {
    // Obtain the two parameters passed from JS.
    size_t argc = 2;
    JSVM_Value args[2] = {nullptr};
    OH_JSVM_GetCbInfo(env, info, &argc, args, nullptr, nullptr);
    // Obtain the index of the element to delete.
    uint32_t index;
    OH_JSVM_GetValueUint32(env, args[1], &index);
    // Delete the element at the specified index.
    bool deleted = true;
    JSVM_Status status = OH_JSVM_DeleteElement(env, args[0], index, &deleted);
    // Convert the boolean value to JSVM_Value and return it.
    JSVM_Value result = nullptr;
    OH_JSVM_GetBoolean(env, deleted, &result);
    if (status != JSVM_OK) {
        OH_LOG_ERROR(LOG_APP, "JSVM DeleteElement fail");
    } else {
        OH_LOG_INFO(LOG_APP, "JSVM DeleteElement: %{public}d", deleted);
    }
    return result;
}
// Register the DeleteElement callback.
static JSVM_CallbackStruct param[] = {
    {.data = nullptr, .callback = DeleteElement},
};
static JSVM_CallbackStruct *method = param;
// Set a property descriptor named deleteElement and associate it with a callback. This allows the DeleteElement callback to be called from JS.
static JSVM_PropertyDescriptor descriptor[] = {
    {"deleteElement", nullptr, method++, nullptr, nullptr, nullptr, JSVM_DEFAULT},
};
// Call the C++ code from JS.
const char *srcCallNative = R"JS(
let arr = [10, 'hello', null, true];
deleteElement(arr, 0);
)JS";

Expected result:

JSVM DeleteElement: 1

OH_JSVM_IsDataview

Use OH_JSVM_IsDataview to check whether a JS object is a DataView object.

CPP code:

// hello.cpp
#include "napi/native_api.h"
#include "ark_runtime/jsvm.h"
#include <hilog/log.h>
// Define OH_JSVM_IsDataview.
static JSVM_Value IsDataView(JSVM_Env env, JSVM_CallbackInfo info) {
    size_t argc = 1;
    JSVM_Value args[1] = {nullptr};
    OH_JSVM_GetCbInfo(env, info, &argc, args, nullptr, nullptr);
    // Call OH_JSVM_IsDataview to check whether the input parameter is a DataView object.
    bool result = false;
    JSVM_Status status = OH_JSVM_IsDataview(env, args[0], &result);
    JSVM_Value isDateView = nullptr;
    OH_JSVM_GetBoolean(env, result, &isDateView);
    if (status != JSVM_OK) {
        OH_LOG_ERROR(LOG_APP, "JSVM IsDataView fail");
    } else {
        OH_LOG_INFO(LOG_APP, "JSVM IsDataView: %{public}d", result);
    }
    return isDateView;
}
// Register the IsDataView callback.
static JSVM_CallbackStruct param[] = {
    {.data = nullptr, .callback = IsDataView},
};
static JSVM_CallbackStruct *method = param;
// Set a property descriptor named isDataView and associate it with a callback. This allows the IsDataView callback to be called from JS.
static JSVM_PropertyDescriptor descriptor[] = {
    {"isDataView", nullptr, method++, nullptr, nullptr, nullptr, JSVM_DEFAULT},
};
// Call the C++ code from JS.
const char *srcCallNative = R"JS(
let buffer = new ArrayBuffer(16);
let dataView = new DataView(buffer);
isDataView(dataView);
)JS";

Expected result:

JSVM IsDataView: 1

OH_JSVM_IsTypedarray

Use OH_JSVM_IsTypedarray to check whether a JS object is a TypedArray object.

CPP code:

// hello.cpp
#include "napi/native_api.h"
#include "ark_runtime/jsvm.h"
#include <hilog/log.h>
// Define OH_JSVM_IsTypedarray.
static JSVM_Value IsTypedarray(JSVM_Env env, JSVM_CallbackInfo info) {
    size_t argc = 1;
    JSVM_Value args[1] = {nullptr};
    OH_JSVM_GetCbInfo(env, info, &argc, args, nullptr, nullptr);
    bool result = false;
    JSVM_Status status = OH_JSVM_IsTypedarray(env, args[0], &result);
    JSVM_Value isTypedArray = nullptr;
    OH_JSVM_GetBoolean(env, result, &isTypedArray);
    if (status != JSVM_OK) {
        OH_LOG_ERROR(LOG_APP, "JSVM IsTypedarray fail");
    } else {
        OH_LOG_INFO(LOG_APP, "JSVM IsTypedarray: %{public}d", result);
    }
    return isTypedArray;
}
// Register the IsTypedarray callback.
static JSVM_CallbackStruct param[] = {
    {.data = nullptr, .callback = IsTypedarray},
};
static JSVM_CallbackStruct *method = param;
// Set a property descriptor named isTypedarray and associate it with a callback. This allows the IsTypedarray callback to be called from JS.
static JSVM_PropertyDescriptor descriptor[] = {
    {"isTypedarray", nullptr, method++, nullptr, nullptr, nullptr, JSVM_DEFAULT},
};
// Call the C++ code from JS.
const char *srcCallNative = R"JS(
isTypedarray(new Uint16Array([1, 2, 3, 4]));
)JS";

Expected result:

JSVM IsTypedarray: 1

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