How to use $children to access child component instances in Vue

How to use $children to access subcomponent instances in Vue

Vue is a JavaScript framework oriented to the MVVM mode. It provides many convenient APIs to create responsive data, control views, etc. Among them, components are an important concept in Vue, which can make the code more modular, reusable, and easy to maintain.

In Vue, each component has its own instance, which can be accessed through this. However, if you want to access the instance of a child component, you need to use the $children attribute. This article will introduce how to use $children to access child component instances.

1. $The meaning of the children attribute

$The children attribute is an array that contains all direct child components in the current component. For example, in a parent component, you can access the instance of the child component in the following way:

this.$children[index]

where index is the index value of the child component in the $children array, starting from 0 .

It should be noted that the $children attribute only includes direct child components, not grandchild components or deeper components. If you want to access all descendant components, you can use recursion to traverse the entire component tree.

2. Accessing child component instances through the ref attribute

In addition to using the $children attribute, you can also access child component instances by using the ref attribute in the parent component. The ref attribute can assign a unique identifier to any component or element, through which the corresponding component or element can be directly accessed.

Add the ref attribute in the child component:

<template>
  <div ref="child">这是一个子组件</div>
</template>

Access the child component instance through the $refs attribute in the parent component:

this.$refs.child

It should be noted that the $refs attribute is An object, its attributes are the identifiers of each ref attribute, and the attribute values ​​correspond to the actual components or elements.

Compared with the $children attribute, the $refs attribute is more flexible and easier to use, because the ref attribute can be added to any component or element without knowing the index value. However, the $refs attribute cannot access indirect subcomponents, and care needs to be taken to avoid naming conflicts.

3. Sample code

The following is a simple sample code that shows how to access the child component instance in the parent component:

Child component:

<template>
  <div ref="child">这是一个子组件</div>
</template>

<script>
export default {
  name: 'ChildComponent'
}
</script>

Parent component:

<template>
  <div>
    <child-component ref="child"></child-component>
  </div>
</template>

<script>
import ChildComponent from '@/path/to/ChildComponent.vue'

export default {
  name: 'ParentComponent',
  components: {
    ChildComponent
  },
  mounted() {
    console.log(this.$children[0]) // 访问第一个子组件实例
    console.log(this.$refs.child) // 通过ref属性访问子组件实例
  }
}
</script>

In the above code, the child component ChildComponent is introduced in the parent component, and <child-component># is used in the template. The ## tag adds a child component. The ref attribute is added to the child component and can be accessed through the $refs attribute in the parent component. $children and $refs are printed in the mounted hook function of the parent component, showing how to access the child component instance.

Summary

In Vue, both the $children attribute and the $refs attribute can be used to access child component instances. The $children attribute is relatively simple and can directly access subcomponents through index values, but cannot access indirect subcomponents; the $refs attribute is more flexible and can add a unique identifier to any component or element, and can access deeper nested components or elements. . In actual development, which method to choose can be flexibly chosen according to specific circumstances.

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