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Preface

In front-end development, Vue and React are two very popular JavaScript frameworks, each with its own unique lifecycle mechanism. Understanding and mastering these lifecycles is essential for developing efficient and maintainable front-end applications. This article will compare the lifecycles of Vue and React in detail to help developers better understand these two frameworks.

Vue's Lifecycle

The life cycle of Vue refers to the entire process from the creation to the destruction of a Vue instance. The life cycle of Vue can be divided into 8 main stages:

1. Creation phase

• beforeCreate: At this stage, the Vue instance has been initialized, but the data observation and event mechanisms have not yet been formed, and the DOM node cannot be obtained (no data and el).
• created: At this point, the Vue instance has been created, and data and methods can be accessed, but the DOM node cannot be obtained (there is data, but no el). This stage is suitable for asynchronous operations and data initialization.

2. Loading phase

• beforeMount: In this transition stage, the root node mounted by Vue has been created, but has not yet been rendered to the page (there are data and el, but the specific DOM cannot be obtained).
• mounted: Both the data and the DOM have been rendered, and operations that depend on the DOM can be performed at this time, such as initializing plug-ins or manipulating the DOM.

3. Update phase

• beforeUpdate: Executed when data update is detected but before DOM update. At this time, the data in the page is still old, but the data in data has been updated.
• updated: Executed after the update is completed, the data in the page and data have been updated.

4. Destruction Phase

• beforeDestroy: Executed when the Vue instance is about to be destroyed. At this time, all data and methods are still available, but are about to be destroyed.
• destroyed: The Vue instance has been destroyed, and all data and methods are unavailable.

React Lifecycle

React's life cycle can be broadly divided into three stages: mounting, rendering, and unmounting. Specifically, it can be subdivided into the following categories:

1. Mounting and unmounting process

• constructor: Used to initialize the state and properties (props) of the React component, receiving props and context as parameters.
• componentWillMount(Deprecated): Executed after the component has initialized data through the constructor, but before the DOM is rendered.
• componentDidMount: The first rendering of the component is completed. At this time, the DOM node has been generated and is suitable for executing AJAX requests or DOM operations.
• componentWillUnmount: Executed when the component is about to be uninstalled, suitable for resource cleanup operations, such as clearing timers or removing event listeners.

2. Update process

• shouldComponentUpdate: Used for performance optimization, controls whether the component is re-rendered. Returning false prevents rendering.
• componentWillReceiveProps(Deprecated, replaced by getDerivedStateFromProps): Executed when the component receives new props, suitable for updating state based on the new props.
• componentWillUpdate: Executed before the component is about to be re-rendered, but it is not recommended to perform DOM operations or data updates here.
• componentDidUpdate: Executed after the component is updated, you can get the props and state before the update.

3. React 16.3 adds lifecycle

• getDerivedStateFromProps: Used to replace componentWillReceiveProps to update the component state according to the new props and state.

Comparison summary

Similarities

• Both provide an opportunity to execute code at different stages of a component's lifecycle.
• Specific logic can be executed during component creation, update, and destruction.

the difference

• design concept: Vue is responsive and based on the concept of mutable data; React is functional and advocates one-way data flow and immutable data.
• Performance Optimization: Vue's performance optimization is relatively automatic, but there may be performance issues when there are too many states; React requires manual performance optimization, but the control is more refined.
• Difficulty: Vue is relatively easier to use, especially for developers with a basic understanding of HTML and JavaScript; React requires more learning and understanding of JSX syntax and React knowledge.

Application Scenario

• For small or medium-sized projects, Vue's ease of use and rapid development capabilities may be more suitable.
• For larger projects, React's flexibility and scalability may be more advantageous.