Detailed explanation of render and h() in vue

Detailed explanation of render and h() in vue

When using Vue.js for front-end development, it is very important to understand and master the "render" function and "h()" function, because they are the core building and rendering parts of the Vue component. render and h() are in
Vue.js Two concepts that are commonly used in creating and rendering Vue components.

What is the "render" function?

The "render" function is an important method of the Vue component. It is used to describe the view structure of the component and is responsible for rendering the virtual DOM tree. The "render" function is a JavaScript function that accepts a createElementparameter named and is used to create a virtual DOM node. This allows you to use JavaScript to build a virtual DOM tree, including elements, components, directives, etc., providing you with greater flexibility.

Basic "render" function example

• renderFunction is an important method of Vue component, which is responsible for rendering the virtual DOM tree of the component.
• renderA function is a JavaScript function that describes the component's view structure. It accepts a createElementmethod as a parameter for creating virtual DOM nodes.
• In renderfunctions, you can use JavaScript to build a virtual DOM tree, including elements, components, directives, etc., which provides you with greater flexibility.
• renderFunctions are usually used in advanced scenarios, such as dynamic components, custom rendering functions, nesting of rendering functions, etc.

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

<script>
export default {
    
    
  data() {
    
    
    return {
    
    
      message: 'Hello, World!'
    };
  },
  render(createElement) {
    
    
    return createElement('div', [
      createElement('p', this.message)
    ]);
  }
}
</script>

In the above example, we have a simple Vue component whose "render" function is used createElementto create a virtual DOM tree and ultimately render an <p>element containing a message.

What is the "h()" function?

The "h()" function (also known as createElement) is a function in Vue 2.x that is used to create VNode objects (virtual DOM nodes). It is the underlying implementation of the "render" function, usually used in Vue templates to declare the structure of components. Vue's compiler will convert the template into a "render" function, and the "h()" function will be used internally to create VNode.

Basic "h()" function example

• h()Function is a simplified method of creating virtual DOM nodes in Vue 2.x. It is createElementan alias for the function used to create VNode objects (virtual DOM nodes).
• h()Functions are usually used in Vue templates to declare the structure of components. Vue's compiler will convert the template into rendera function, and h()the function will be used internally to create VNode.
• h()Functions are more suitable for regular component definitions and provide sufficient convenience for most cases.

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

<script>
export default {
    
    
  data() {
    
    
    return {
    
    
      message: 'Hello, World!'
    };
  },
  render(createElement) {
    
    
    return createElement('div', [
      createElement('p', this.message)
    ]);
  }
}
</script>

In this example, we use Vue templates to declare the structure of the component, and the compiler will convert it into a call to the "h()" function, ultimately generating a virtual DOM.

Why use the "render" function and the "h()" function?

1. Flexibility : The "render" function and the "h()" function allow you to build and customize components programmatically, which is especially useful in advanced scenarios that require dynamically generated component structures.

2. Performance optimization : Manually creating a virtual DOM can provide more granular control and help with performance optimization. You can avoid unnecessary rendering and only update what needs to be updated.

3. Type checking : The "h()" function and the "render" function can be used in conjunction with type checking tools such as TypeScript to provide type-safe component construction.

Summarize:

• renderThe function is more flexible and suitable for advanced scenarios, requiring manual creation of virtual DOM.
• h()Functions are simplified syntactic sugar for regular component definitions, often used in templates, and are easier to read and write.
• The "render" function and the "h()" function are key parts of Vue component construction and rendering. They provide advantages in flexibility, performance optimization, and type checking, making Vue a powerful front-end framework. To make full use of these two functions,

In Vue 3.x, Vue has abandoned h()functions and uses renderfunctions to define components, making component definitions more consistent and no longer requiring h()function aliases. However, these concepts are still important in Vue 2.x versions.

The above is the detailed explanation of render and h() in Tvue. Thank you for reading.
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