Use provide and inject in Vue to implement data transfer and performance optimization between components

Use provide and inject in Vue to achieve data transfer and performance optimization between components

In Vue, data transfer between components is a very common requirement. Sometimes we want to provide data at a node in the component tree and then use the data in its descendant components. In this case, we can use Vue's provide and inject to achieve this. In addition to data transfer, provide and inject can also be used for performance optimization, reducing the level of props transfer and improving component performance.

provide and inject are advanced features of Vue that can inject data into component instances, making them available throughout the component tree. Its use is very simple. Let's look at an example first:

// 父组件
export default {
  provide: {
    message: 'Hello from parent'
  }
}

// 子组件
export default {
  inject: ['message'],
  mounted() {
    console.log(this.message); // 输出：Hello from parent
  }
}

In the parent component, we provide a message data through the provide option, and then inject this data through the inject option in the child component. The data provided by the parent component can be accessed through this.message in the child component.

In addition to providing a single data, we can also provide an object containing multiple data. In the provide option, we can use a function to return an object, so that data can be provided dynamically.

// 父组件
export default {
  provide() {
    return {
      message: 'Hello from parent',
      count: 1
    }
  }
}

In the child component, inject this object through the inject option, and you can directly access the data in it.

// 子组件
export default {
  inject: ['message', 'count'],
  mounted() {
    console.log(this.message); // 输出：Hello from parent
    console.log(this.count);   // 输出：1
  }
}

One of the benefits of using provide and inject is that data transfer between components is more concise and reduces the props hierarchy. Especially when passing data across level components, the props method seems very cumbersome. Using provide and inject can reduce code redundancy and improve development efficiency.

Another benefit is improved component performance. When using props for data transfer, each layer of components needs to use props to transfer data, and props are one-way and can only be transferred from upper-level components to lower-level components. Using provide and inject can skip intermediate components and pass data directly to the required components.

The following example can better illustrate this problem:

// 父组件
export default {
  data() {
    return {
      count: 1
    }
  },
  provide() {
    return {
      message: 'Hello from parent',
      getCount: () => this.count
    }
  }
}

// 子组件A
export default {
  inject: ['message', 'getCount'],
  mounted() {
    console.log(this.message);   // 输出：Hello from parent
    console.log(this.getCount()); // 输出：1
  }
}

// 子组件B
export default {
  inject: ['message', 'getCount'],
  mounted() {
    console.log(this.message);   // 输出：Hello from parent
    console.log(this.getCount()); // 输出：1
  }
}

// 子组件C
export default {
  inject: ['message', 'getCount'],
  mounted() {
    console.log(this.message);   // 输出：Hello from parent
    console.log(this.getCount()); // 输出：1
  }
}

In this example, the parent component provides a data and a method, and then injects it into the subcomponent A and subcomponent through the provide option. In component B and sub-component C. We can see that regardless of the level of the child component, the data and methods of the parent component can be directly accessed.

To summarize, Vue's provide and inject are a very convenient way to transfer data between components, which not only simplifies the code, but also improves performance. But it should be noted that provide and inject are non-responsive features, that is, when the data provided by provide changes, the re-rendering of the sub-component will not be triggered. Therefore, when using provide and inject, you need to pay attention to the update of data.

The above is an introduction to using provide and inject in Vue to achieve data transfer and performance optimization between components. I hope it will be helpful to you.

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