Vue component communication: using custom events for cross-level communication

Vue component communication: using custom events for cross-level communication

In Vue development, component communication is a very important topic. As the complexity of the project increases, the communication between components also becomes more complex. Vue provides a variety of ways to communicate between components, such as props and vuex. But sometimes, we need to communicate between parent and grandchild components. At this time, using custom events is a very convenient way.

In Vue, each component is an instance, and custom events can be triggered and monitored through the $emit method and $on method of the instance. Below I will use a simple example to demonstrate how to use custom events for cross-level communication.

First, we create a parent component Parent and a grandchild component Grandchild. There is a button in the Parent component. Clicking the button will trigger a custom event "messageEvent". The Grandchild component will listen to the event and execute the corresponding callback function.

The parent component code is as follows:

<template>
  <div>
    <button @click="sendMessage">发送消息给孙子</button>
    <child></child>
  </div>
</template>

<script>
import Vue from "vue";
import child from "./child";

export default {
  components: {
    child
  },
  methods: {
    sendMessage() {
      Vue.prototype.$bus.$emit("messageEvent", "Hello Grandchild!");
    }
  }
};
</script>

The grandson component code is as follows:

<template>
  <div>
    <p>{{ message }}</p>
  </div>
</template>

<script>
export default {
  data() {
    return {
      message: ""
    };
  },
  mounted() {
    this.$bus.$on("messageEvent", message => {
      this.message = message;
    });
  }
};
</script>

In this example, we use Vue’s prototype property $bus to implement the event bus function . In the parent component, we triggered the custom event "messageEvent" through the Vue.prototype.$bus.$emit method and passed a string parameter as the message content. In the grandchild component, we listened to the "messageEvent" event through the this.$bus.$on method and updated the message value in the callback function.

In this way, we achieve communication between the parent component and the grandchild component. When the button is clicked, the parent component will trigger the custom event "messageEvent", and then the grandchild component will receive the event and update the corresponding message content. This completes the cross-level communication operation.

In addition to simple string parameters, we can also pass more complex objects or data. You only need to pass the data to be passed as the second parameter of the emit method, and then receive the data through the parameters of the callback function when listening to the event.

To summarize, using custom events for cross-level component communication is a flexible and convenient way. Through Vue's $emit and $on methods, we can achieve data transfer and synchronization between parent components and grandchild components. In actual projects, we can flexibly use this method according to specific needs to improve the interaction between components.

Code example, in actual development, the corresponding parent components and grandchild components need to be imported into the project and registered. At the same time, you need to pay attention to the naming convention of the code and the organizational structure between components.

I hope this article will help you understand Vue component communication and use custom events for cross-level communication!

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