Introduction to the usage and precautions of Mixin in Vue

Vue.js is one of the most popular front-end frameworks in web development today. It provides a first-class development experience for building large, flexible and efficient web applications. One of the features of Vue.js is that it supports mixins, a useful concept that allows us to share some common code among different components.

This article will introduce the specific usage and precautions of Mixin in Vue.

1. The concept of Mixin

Mixin is a code reuse mechanism that allows us to share some common code between different components. In Vue, a Mixin is a JavaScript object that can contain any properties and methods in the component.

In actual development, we often encounter multiple components with similar functions or requirements. At this time, Mixin can come in handy. We only need to abstract the same code and encapsulate it into a Mixin Object, and then introduce the Mixin object into the components that need to use these codes.

2. How to use Mixin

In Vue, we can introduce Mixin objects through the mixins option, as shown below:

const myMixin = {
  data() {
    return {
      message: 'Hello, World!'
    }
  },
  created() {
    console.log('Mixin created!');
  },
  methods: {
    sayHi() {
      console.log('Hi, there!');
    }
  }
};

Vue.component('my-component', {
  mixins: [myMixin],
  created() {
    console.log('my-component created!');
  },
  methods: {
    greet() {
      console.log(this.message);
      this.sayHi();
    }
  }
});

In the above example, we define A Mixin object named myMixin is created, which contains a message attribute, a created life cycle function and a sayHi method.

Next, myMixin is introduced in the my-component component, so that this component can access all properties defined in myMixin and methods.

In the my-component component, we override the greet method, which can call message and sayHi method, and also executes the original created life cycle function.

3. Notes on Mixin

1. Options with the same name will be merged

When both components and Mixin define the same options, these options will be merged merge. For most options, we can complete the merging through Vue's merging strategy, but for some specific options, such as data, methods, etc., they will be merged into a function array, and the order of execution is that Mixin is executed first, and then components.

For example:

const mixin1 = {
  data() {
    return {
      message: 'Hello, World!',
      name: 'Mixin1'
    }
  },
  created() {
    console.log('Mixin1 Created!');
  }
};

const mixin2 = {
  data() {
    return {
      name: 'Mixin2'
    }
  },
  created() {
    console.log('Mixin2 Created!');
  }
};

Vue.component('my-component', {
  mixins: [mixin1, mixin2],
  data() {
    return {
      message: 'Hello, Vue!'
    }
  },
  created() {
    console.log('my-component Created!');
  },
  methods: {
    greet() {
      console.log(this.message);
    }
  }
});

In the above example, both Mixins define the data and created options, and the componentmy-component also defines the same data options, but the content they define is different. At this time, data will be merged into a function array and executed in the defined order.

The execution result is as follows:

Mixin1 Created!
Mixin2 Created!
my-component Created!

2. Mixin will affect the code organization of the component

After using Mixin, our code organization Corresponding changes will occur. Because Mixin extracts the common logic in the component, the core code of the component will become more concise.

However, if we use too many Mixins, it will make the code difficult to maintain and understand. Therefore, when using Mixin, we need to follow the following principles:

• Only use Mixin in the logic shared between different components
• Plan the code structure reasonably and avoid deep inheritance
• Avoid defining data attributes in Mixin, otherwise it will lead to data confusion

3. Summary

Mixin is a very powerful feature in Vue.js, it can Let us easily achieve code reuse and improve code reusability and maintainability. At the same time, we also need to pay attention to the usage and precautions of Mixin to prevent potential problems. Hope this article can help you better understand the Mixin feature in Vue.js.

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