Using $listeners to pass event handling functions in Vue

In Vue, there are often some nested components, and events need to be passed between these nested components. In Vue, the $emit event is used for event communication between components.

However, in some cases, we need to pass the event handling function of a parent component to the nested child component. At this time, using the $emit event is not appropriate. At this time, you can use the $listeners provided by Vue to pass the event processing function.

So, what are $listeners? $listeners is a special property in the Vue instance object, which contains all listeners/event handlers that act on the component.

Through the $listeners attribute, we can pass the event handling function defined in the parent component to the nested child component for use:

1. The event handling function defined in the parent component:

<template>
  <div>
    <button @click="handleClick">Click me</button>
    <child @childClick="$listeners.childClick"></child>
  </div>
</template>

<script>
  export default {
    methods: {
      handleClick() {
        console.log('parent click')
      }
    }
  }
</script>

2. The child component receives the event handling function passed by the parent component:

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

<script>
  export default {
    methods: {
      handleClick() {
        this.$emit('childClick')
      }
    }
  }
</script>

In this way, the event handling function defined in the parent component can be passed Used in child components.

It should be noted that the event handling function passed in the parent component needs to be attribute bound with v-on. At the same time, it should be noted that the event name cannot be the same as the event name defined by the child component, otherwise a conflict will occur.

In addition, the $listeners property only contains event listeners passed to the current component, and does not include listeners passed to other child components in the parent component. Therefore, it is important to note that event handlers bound in child components need to be properly propagated to other child components in the parent component.

In short, using $listeners in Vue is a convenient and effective way to pass event processing functions, which allows us to communicate events more flexibly between components.

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