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Vue is a popular front-end framework that provides many convenient functions and APIs, including componentization. In Vue, we can split a page into multiple small components, each with its own state and methods, which makes the code clearer and easier to maintain.

In Vue, the parent component can pass data to the child component through the props attribute, but how does the child component call the parent component's method and pass parameters? This requires the use of the event mechanism provided in Vue.

First, define a method in the parent component, for example:

<template>
  <div>
    <child-component @child-click="handleChildClick"></child-component>
  </div>
</template>

<script>
import ChildComponent from './ChildComponent.vue'

export default {
  components: {
    ChildComponent
  },
  methods: {
    handleChildClick(data) {
      console.log('child click:', data)
    }
  }
}
</script>

In the above code, we define a handleChildClickmethod in the parent component, @child-clicklisten to the click event of the child component through the event, and set the event callback function to handleChildClickthe method.

Next, trigger the parent component's method in the child component, for example:

<template>
  <div>
    <button @click="handleClick">Click me</button>
  </div>
</template>

<script>
export default {
  methods: {
    handleClick() {
      this.$emit('child-click', 'hello')
    }
  }
}
</script>

In the above code, we define a handleClickmethod in the child component and this.$emit(‘child-click’, ‘hello’)trigger an child-clickevent called through and set the parameter to 'hello'.

Finally, we can get the parameters passed by the child component in the handleChildClick method of the parent component, for example:

handleChildClick(data) {
  console.log('child click:', data) // Output：child click: hello
}

In the above code, we handleChildClickoutput the parameter passed by the child component, namely 'hello', in the method of the parent component.

In summary, the method for a child component to call a parent component method and pass parameters is to trigger a custom event in the child component, set the event callback function to the method in the parent component, and then listen to the event through the $emit method in the parent component and obtain the parameters passed by the child component. This can achieve communication between the child component and the parent component.

For example, suppose we have a parent component and a child component. There is a method called handleChildClick in the parent component and a button in the child component. Clicking the button needs to trigger the handleChildClick method of the parent component and pass a parameter. The code is as follows:

Parent component code:

<template>
  <div>
    <child-component @child-click="handleChildClick"></child-component>
  </div>
</template>

<script>
import ChildComponent from './ChildComponent.vue'

export default {
  components: {
    ChildComponent
  },
  methods: {
    handleChildClick(data) {
      console.log('child click:', data)
      // Here you can do some processing, such as updating the status of the parent component
      this.parentData = data
    }
  },
  data() {
    return {
      parentData: ''
    }
  }
}
</script>

Subcomponent code:

<template>
  <div>
    <button @click="handleClick">Click me</button>
  </div>
</template>

<script>
export default {
  methods: {
    handleClick() {
      this.$emit('child-click', 'hello')
    }
  }
}
</script>

In the above code, we define a button in the child component and trigger an child-clickevent called in the button's click event, and set the parameter to 'hello'.

In the parent component, we define a handleChildClickmethod named , and @child-clicklisten to the click event of the child component through the event, and set the event callback function to handleChildClickthe method. In handleChildClickthe method, we can get the parameters passed by the child component and do some processing, such as updating the status of the parent component.

Finally, we can get the parameters passed by the child component in the parent component and save them in parentData.

Summarize

In Vue, a child component can call a parent component method and pass parameters by triggering a custom event in the child component, setting the event callback function to the method in the parent component, and then $emitlistening to the event through the method in the parent component and obtaining the parameters passed by the child component. This allows communication between the child component and the parent component.

Through the above examples, we can see how to implement Vue in which child components call parent component methods and pass parameters. This method can well solve the communication problem between components, making the code clearer and easier to maintain.