SoFunction
Updated on 2025-04-04

Detailed explanation of how Vue virtual DOM improves front-end development efficiency

Preface

With the continuous development of front-end technology, more and more frameworks and libraries have emerged, and they have become one of the most popular front-end frameworks. The idea of ​​responsive data binding and componentization is adopted, allowing developers to build interactive user interfaces more efficiently. The underlying principle involves many concepts and technologies, among which virtual DOM is one of the core concepts. This article will introduce the principles and applications of Vue virtual DOM from the following aspects.

1. What is a virtual DOM

Virtual DOM is a lightweight JavaScript object used to describe the structure and properties of a real DOM tree. In this case, when the data changes, the differences between the old and new virtual DOMs will be compared first, and then only the parts that need to be updated will be updated, thereby avoiding frequent DOM operations and improving performance. The concept of virtual DOM was first introduced by React, and also borrowed from React's ideas and applied it to its own framework.

2. Advantages of virtual DOM

The emergence of virtual DOM is mainly to solve the performance problems caused by frequent operation of DOM in front-end development. In traditional front-end development, when data changes, we need to directly operate the DOM, such as adding, deleting, modifying nodes, etc. Doing so will result in frequent DOM operations, which will affect performance. The emergence of virtual DOM can convert DOM operations into operations of JavaScript objects, thereby avoiding frequent DOM operations and improving performance. In addition, virtual DOM also has the following advantages:

(1) Improve development efficiency

During the development process, we can first use a virtual DOM for development and debugging, and then convert it into a real DOM for deployment. This can improve development efficiency and facilitate debugging and testing.

(2) Cross-platform compatibility

Virtual DOM can run on different platforms, such as browsers, etc. This can improve cross-platform compatibility and also facilitate multi-terminal development.

(3) Improve maintainability

Virtual DOM can separate the structure and style of components, thereby improving the maintainability of the code. In addition, the virtual DOM can split the components into multiple widgets, thereby improving code reusability and maintainability.

3. The principle of virtual DOM

The principle of virtual DOM mainly includes the following aspects:

(1) The structure of virtual DOM

The structure of a virtual DOM mainly includes node type, node attributes and child nodes. Among them, the node type can be an element node, a text node, annotation node, etc.; the node attributes can include class, style, id, etc.; the child nodes can be other virtual DOM objects or text nodes.

(2) Creation of virtual DOM

In this, the creation of the virtual DOM is implemented through the rendering function. A rendering function is a piece of JavaScript code used to generate a virtual DOM. In the rendering function, we can use the provided template syntax, such as {{}} expressions, v-if directives, v-for directives, etc., to generate a virtual DOM object.

('my-component', {
  render: function (createElement) {
    return createElement(
      'div',
      { class: 'my-component' },
      [
        createElement('h1', 'Hello World'),
        createElement('p', 'This is my component')
      ]
    )
  }
})

In the above code, we use the method to create a component named my-component. In the component's render function, we use the createElement method to create a div element and add two child elements h1 and p. The first parameter of the createElement method represents the node type, the second parameter represents the node attribute, and the third parameter represents the child node.

(3) Update of virtual DOM

When the data changes, frequent DOM operations will be avoided by comparing the differences between the old and new virtual DOMs first, and then only the parts that need to be updated. When comparing the differences between old and new virtual DOMs, the Diff algorithm is used, which can quickly compare the differences between two objects, thereby improving performance.

<div >
  <p>{{ message }}</p>
  <button v-on:click="updateMessage">Update Message</button>
</div>

In the above code, we bind the message variable to the p element. When the data changes, the virtual DOM is automatically updated and the updated results are rendered on the page. We can bind events through the v-on directive, such as updating the value of the message variable when clicking a button.

4. Application of virtual DOM

The application of virtual DOM mainly includes the following aspects:

(1) Component development

In this, we can split a page into multiple widgets, each of which is an independent module that can contain its own templates, styles, and logic. Componentization can improve code reusability and maintainability, thereby developing applications more efficiently.

('my-component', {
  template: `
    <div class="my-component">
      <h1>{{ title }}</h1>
      <p>{{ content }}</p>
    </div>
  `,
  data: function () {
    return {
      title: 'Hello World',
      content: 'This is my component'
    }
  }
})

In the above code, we create a component called my-component. The component's template contains an h1 element and a p element, which displays the values ​​of title and content variables respectively. The initial values ​​of title and content variables are defined in the data options of the component.

(2) Performance optimization

Virtual DOM can avoid frequent DOM operations, thereby improving performance. In this case, when the data changes, the differences between the old and new virtual DOMs will be compared first, and then only the parts that need to be updated will be updated, thereby avoiding frequent DOM operations and improving performance.

('my-component', {
  template: `
    <div class="my-component">
      <h1>{{ title }}</h1>
      <p>{{ content }}</p>
    </div>
  `,
  data: function () {
    return {
      title: 'Hello World',
      content: 'This is my component'
    }
  },
  shouldComponentUpdate: function (newProps, newState) {
    if ( ===  &&  === ) {
      return false
    } else {
      return true
    }
  }
})

In the above code, we override the shouldComponentUpdate method to determine whether the title and content variables of the component have changed. If there is no change, it will return false, otherwise it will return true. Doing so avoids unnecessary DOM operations, thereby improving performance.

(3) Cross-platform compatibility

Virtual DOM can run on different platforms, such as browsers, etc. This can improve cross-platform compatibility and also facilitate multi-terminal development.

// Run in the browsernew Vue({
  el: '#app',
  data: {
    message: 'Hello World'
  }
})

// Run inconst Vue = require('vue')
const app = new Vue({
  data: {
    message: 'Hello World'
  }
})

In the above code, we create a Vue instance in the browser and define a message variable. Virtual DOM can run on both platforms, improving cross-platform compatibility.

(4) Development efficiency

During the development process, we can first use a virtual DOM for development and debugging, and then convert it into a real DOM for deployment. This can improve development efficiency and facilitate debugging and testing.

('my-component', {
  render: function (createElement) {
    return createElement(
      'div',
      { class: 'my-component' },
      [
        createElement('h1', 'Hello World'),
        createElement('p', 'This is my component')
      ]
    )
  }
})
// Render the virtual DOM on the pagenew Vue({
  el: '#app',
  render: function (createElement) {
    return createElement('my-component')
  }
})

In the above code, we first define a component named my-component, and then use the createElement method in the render function of the Vue instance to create a my-component element and render it on the page. This can improve development efficiency and facilitate debugging and testing.

Summarize

The underlying principle is based on the following core concepts and technologies:

  • Virtual DOM: Use virtual DOM to describe the page structure, and update the page by comparing the differences between new and old virtual DOMs to improve rendering performance.
  • Template compilation: Compile the template into a rendering function to generate a virtual DOM. During the template compilation process, syntax analysis, AST generation, optimization and code generation will be performed.
  • Responsive data binding: Use data hijacking and publish subscription models to implement responsive data binding. When data changes, the relevant virtual DOM and page will be automatically updated.
  • Componentization: Split the page into multiple widgets, each of which is an independent module that can contain its own templates, styles, and logic, thereby improving the reusability and maintainability of the code.

Understanding these principles can help us better understand the working principles and develop more efficiently

The above is a detailed explanation of how Vue virtual DOM improves front-end development efficiency. For more information on Vue virtual DOM improving development efficiency, please pay attention to my other related articles!