Programming tips and precautions for Vue component communication

Programming tips and precautions for Vue component communication

Vue.js is a popular JavaScript framework. Due to its simplicity, ease of use and powerful data binding capabilities, more and more developers choose it. Use Vue to develop front-end applications. In the development process of Vue, component communication is a very important topic. Good component communication can improve development efficiency and code maintainability. This article will introduce some programming skills and precautions for Vue component communication.

1. Parent-child component communication
In Vue, parent-child component communication is the most common way. The parent component passes data to the child component through props, and the child component passes data to the parent component through events.

1. Use props to pass data

Parent components can pass data to child components through props. Child components can receive data passed by parent components and perform rendering or other operations.

// 父组件
<template>
  <div>
    <child-component :message="message" />
  </div>
</template>

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

export default {
  components: {
    ChildComponent
  },
  data() {
    return {
      message: 'Hello Vue!'
    }
  }
}
</script>

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

<script>
export default {
  props: ['message']
}
</script>

In the above code, the parent component passes message to the child component through props, and the child component uses the props option to declare the received properties.

2. Use events to pass data

The child component can trigger a custom event through the $emit method and pass the data to the parent component. The parent component can listen to the events triggered by the child component through v-on and obtain the passed data.

// 子组件
<template>
  <button @click="handleClick">点击我触发事件</button>
</template>

<script>
export default {
  methods: {
    handleClick() {
      this.$emit('my-event', 'Hello Parent!')
    }
  }
}
</script>

// 父组件
<template>
  <div>
    <child-component @my-event="handleEvent" />
  </div>
</template>

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

export default {
  components: {
    ChildComponent
  },
  methods: {
    handleEvent(message) {
      console.log(message)
    }
  }
}
</script>

In the above code, the child component triggers the my-event event through the this.$emit method and sends the data 'Hello Parent!' Passed to the parent component. The parent component uses v-on to listen to the my-event event and calls the corresponding method to handle the event.

2. Non-parent-child component communication
In addition to parent-child component communication, sometimes we also need to communicate between non-parent-child components. Commonly used methods include using a Vue instance as a central event bus or using Vuex for state management.

1. Use a Vue instance as the central event bus

You can create a Vue instance as the central event bus. Subcomponents trigger events through this instance, and other components receive data by listening to events.

// EventBus.js
import Vue from 'vue';
export const EventBus = new Vue();

// 子组件A
<template>
  <button @click="handleClick">点击我触发事件</button>
</template>

<script>
import { EventBus } from './EventBus.js';

export default {
  methods: {
    handleClick() {
      EventBus.$emit('my-event', 'Hello!')
    }
  }
}
</script>

// 子组件B
<template>
  <div>
    <p>{{ message }}</p>
  </div>
</template>

<script>
import { EventBus } from './EventBus.js';

export default {
  data() {
    return {
      message: ''
    }
  },
  mounted() {
    EventBus.$on('my-event', (message) => { 
      this.message = message;
    })
  }
}
</script>

In the above code, we created a Vue instance named EventBus and implemented communication between sub-components through this instance. Subcomponent A triggers the custom event my-event through EventBus.$emit, and subcomponent B listens to my-event# through EventBus.$on ##Events and update data.

2. Use Vuex for state management

Vuex is a state management library officially provided by Vue. You can use Vuex to manage the state of your application and implement communication between components.

// store.js
import Vue from 'vue';
import Vuex from 'vuex';

Vue.use(Vuex);

export default new Vuex.Store({
  state: {
    message: ''
  },
  mutations: {
    setMessage(state, message) {
      state.message = message;
    }
  },
  actions: {
    updateMessage({ commit }, message) {
      commit('setMessage', message);
    }
  },
  getters: {
    getMessage(state) {
      return state.message;
    }
  }
});

// 子组件A
<template>
  <button @click="handleClick">点击我触发事件</button>
</template>

<script>
import { mapActions } from 'vuex';

export default {
  methods: {
    ...mapActions(['updateMessage']),
    handleClick() {
      this.updateMessage('Hello Vuex!');
    }
  }
}
</script>

// 子组件B
<template>
  <div>
    <p>{{ message }}</p>
  </div>
</template>

<script>
import { mapGetters } from 'vuex';

export default {
  computed: {
    ...mapGetters(['getMessage']),
    message() {
      return this.getMessage;
    }
  }
}
</script>

In the above code, we use

Vuex to create a store, including state, mutations, actions and getters. Subcomponent A updates the value of message by calling the updateMessage method through the mapActionsauxiliary function. Subcomponent B obtains the value of message through the mapGetters auxiliary function.

3. Notes

Make good use of computed properties: In Vue, computed properties are a very useful feature. Using calculated attributes can avoid writing complex expressions in templates, and can also cache the results of multiple data attribute calculations to improve performance.
1. Try to avoid modifying props directly: In Vue, props are read-only, and the value of props should not be modified directly. If you need to modify the value of props in a subcomponent, you should convert it to the data attribute of the subcomponent and modify it inside the subcomponent. If you need to pass the modified value to the parent component, you can use the emit event.
2. Use $refs to get sub-component instances: In some scenarios, we want to get the sub-component instance in the parent component, you can use $refs. By adding the ref attribute to the child component, the child component instance can be obtained through this.$refs in the parent component.

Summary

In Vue component communication, parent-child component communication and non-parent-child component communication are the two most common ways. Parent-child component communication can realize data transfer and interaction through props and events. Non-parent-child component communication can be achieved by creating a Vue instance as a central event bus or using Vuex for state management. When writing Vue component communication code, we should make good use of calculated properties, avoid directly modifying props, and use $refs to obtain subcomponent instances and other techniques to improve development efficiency and code maintainability.

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