harmony 鸿蒙Lifecycle Definition

2022-08-09
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Lifecycle Definition

NOTE

This component is supported since API version 5. Updates will be marked with a superscript to indicate their earliest API version.

A range of lifecycle callbacks are provided for custom components, including onInit, onAttached, onDetached, onLayoutReady, onDestroy, onShow, and onHide. You can use these callbacks to manage the internal logic of your custom components. The following describes the times when the lifecycle callbacks are invoked.

Attribute	Type	Description	Invoked When
onInit	Function	Custom component initialization	The custom component is created. This callback is invoked once.
onAttached	Function	Custom component loading	The custom component is added to the <Page> component tree. When this callback is invoked, related data can be displayed during the lifecycle in scenarios such as image loading and animation playback.
onLayoutReady	Function	Component layout completion	Layout calculation, including content size and position adjustment, is complete for the custom component.
onDetached	Function	Custom component detachment	The custom component is detached. It is usually used to stop animation or asynchronous logic execution.
onDestroy	Function	Custom component destruction	The custom component is destroyed. It is usually used to release resources.
onShow	Function	Page display of a custom component	The page where the custom component is located is displayed.
onHide	Function	Page hiding of a custom component	The page where the custom component is located is hidden.

Example

<!-- comp.hml -->
<div class="item">  
   <text class="text-style">{{ value }}</text>  
</div>

//comp.js
export default {
  data: {
    value: "Create a component."
  },
  onInit() {
    console.log("Component created.")
  },
  onAttached() {
    this.value = "Load the component."
    console.log ("Component loaded.")
  },
  onShow() {
    console.log ("Page displayed.")
  },
  onHide() {
    console.log ("Page hidden.")
  }
}