What life cycles will be triggered by Vue component updates?

Vue is a popular JavaScript framework for building interactive user interfaces. Components in Vue are an important concept, and many developers are gradually adopting a component-based approach to building front-end applications. This article will explore which life cycles are triggered by Vue component updates.

The Vue component update life cycle can be divided into three stages: before update, during update, and after update. Each stage has specific lifecycle functions that are responsible for handling events and tasks that occur in that stage.

1. Pre-update phase

When the component is updated, Vue will trigger the following life cycle functions:

beforeUpdate: before the component is re-rendered transfer. This function can be used to perform certain tasks before updating, such as updating a computed property within a component or refreshing data in a child component. Changes made in this function will be committed to the DOM tree.

The corresponding sample code is as follows:

beforeUpdate() {
  console.log('组件更新前执行...');
}

2. Updating stage

When the component is currently rendered and updated, Vue will trigger the following life cycle function:

render: When re-rendering a component, Vue will call the component's rendering function. In this function, Vue will compare the old and new virtual DOM and send the final updated content to the browser's DOM tree.

updated: After the component update is completed, it is called after all sub-components are updated. Within this function, you can perform certain tasks or refresh UI components in response to the updated state. It should be noted that in the updated hook function, you should try to avoid modifying the state within the component, otherwise it may cause unnecessary component re-rendering.

The corresponding sample code is as follows:

render(h) {
  console.log('组件重新渲染...');
  return h('div', 'Hello World');
},
updated() {
  console.log('组件更新完成...');
}

3. Post-update phase

When the component update is completed, Vue will trigger the following life cycle function:

activated: This function will be called when the parent component of the containing component is activated. In this function, you can perform any necessary tasks, such as pulling new data, updating status, etc.

deactivated: This function will be called when the parent component containing the component is deactivated. In this function, you can perform any necessary cleanup tasks, such as canceling timers, releasing resources, etc.

The following is a sample code:

activated() {
  console.log('组件被激活...');
},
deactivated() {
  console.log('组件被失活...');
}

Summary

In general, the life cycle hook functions involved in Vue component updates include: beforeUpdate, render, updated, activated and deactivated. These lifecycle functions are automatically managed by Vue, allowing developers to respond to and handle component state updates and changes. Therefore, the importance of understanding the role of these lifecycle hooks and how to utilize them cannot be ignored when doing Vue component updates.

The above is the detailed content of What life cycles will be triggered by Vue component updates?. For more information, please follow other related articles on the PHP Chinese website!