Lifecycle Definition

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

We provide a range of lifecycle callbacks for custom components, including onInit, onAttached, onDetached, onLayoutReady, onDestroy, onPageShow, and onPageHide. 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	Called When
onInit	Function	Custom component initialization	Triggered once, when a custom component is created.
onAttached	Function	Custom component loading	Triggered when a custom component is added to the <Page> component tree. When this callback is triggered, related data can be displayed during the lifecycle in scenarios such as image loading and animation playback.
onLayoutReady	Function	Component layout completion	Triggered when layout calculation, including content size and position adjustment, is complete for a custom component.
onDetached	Function	Custom component removal	Triggered when a custom component is removed. It is usually used to stop animation or asynchronous logic execution.
onDestroy	Function	Custom component destruction	Triggered when a custom component is destroyed. It is usually used to release resources.
onPageShow	Function	Page display of a custom component	Triggered when the page where a custom component is located is displayed.
onPageHide	Function	Page hiding of a custom component	Triggered when the page where a 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."
  },
  onDetached() {
    this.value = ""
  },
  onPageShow() {
    console.log ("Page displayed.")
  },
  onPageHide() {
    console.log ("Page hidden.")
  }
}