A brief analysis of how vue calls component methods

Vue is a popular JavaScript framework that makes it easier to build a scalable and maintainable web application. One of the important features is its componentized architecture, which can use components to encapsulate code blocks to improve code reusability and maintainability. In Vue, component methods are very important. This article will introduce how to call component methods.

In Vue, component methods can be defined in the component. We can define a component using the Vue.extend method and define methods in the methods attribute of the component object. For example:

var MyComponent = Vue.extend({
  methods: {
    myMethod: function () {
      // 这是一个方法代码块
    }
  }
})

We can call the component's method by instantiating the component object and calling the method on the instance:

var componentInstance = new MyComponent()
componentInstance.myMethod()

The above code first creates a MyComponent component object, and then Create an instance componentInstance of this object and call the myMethod method in it.

We can also use a component as a subcomponent of another component and call the method of the subcomponent through the reference of the parent component. In Vue, components can communicate through property passing. A parent component can reference a child component instance using the child component's ref attribute and call its methods directly. The sample code is as follows:

<template>
  <div>
    <child-component ref="child"></child-component>
    <button @click="callChildMethod">调用子组件方法</button>
  </div>
</template>

<script>
  import ChildComponent from './ChildComponent.vue';
  
  export default {
    components: {
      'child-component': ChildComponent
    },
    methods: {
      callChildMethod: function () {
        this.$refs.child.childMethod()
      }
    }
  }
</script>

In the above code, the parent component defines the reference of the child component through ref="child", and then references the child component through this.$refs.child in the method callChildMethod, and calls the childMethod method.

Of course, if a component is used in many ways, it will be troublesome for the sub-component to call its own method. We can use Vue's built-in event system to directly execute the methods that child components need to call in the parent component through custom event listening. Custom events can be triggered through the $emit method of the child component and listened to through the v-on directive of the parent component. The sample code is as follows:

<!-- ChildComponent.vue -->
<template>
  <div>
    <!-- 子组件中触发自定义事件 -->
    <button @click="$emit(&#39;my-event&#39;)">触发自定义事件</button>
  </div>
</template>

<script>
  export default {
    methods: {
      childMethod: function () {
        // 这是子组件的方法代码块
      }
    }
  }
</script>

<!-- ParentComponent.vue -->
<template>
  <div>
    <child-component @my-event="parentMethod"></child-component>
  </div>
</template>

<script>
  import ChildComponent from './ChildComponent.vue';
  
  export default {
    components: {
      'child-component': ChildComponent
    },
    methods: {
      parentMethod: function () {
        // 这是父组件的方法代码块
      }
    }
  }
</script>

In the above code, the custom event "my-event" is triggered in the child component, and then the event is listened to through the v-on directive in the parent component and bound to parentMethod method, thereby calling the child component's method in the parent component.

In short, in Vue, there are many ways to call component methods. We can choose different ways to implement our functions according to the actual situation. At the same time, in actual development, we need to pay attention to the scope and scope of methods to ensure the maintainability and reusability of the code.

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