VUE3 basic tutorial: How to use Vue life cycle hooks

Vue3 Basics Tutorial: How to Use Vue Lifecycle Hooks

Vue.js is a popular JavaScript library that provides an extensible framework for creating dynamic web applications. Vue.js version 3 has been released. Vue3 provides more features and functions based on the Composition API.

Vue lifecycle hooks (lifecycle hooks) are an important concept in Vue.js, which provide the ability to execute specific code at different stages. This article will take an in-depth look at Vue lifecycle hooks and their usage.

Vue component life cycle

In Vue.js, each component goes through a series of stages, from creation to destruction. These stages are called the Vue component lifecycle.

The Vue component life cycle is divided into 3 main stages:

1. Creation cycle
2. Update cycle
3. Destruction cycle

Each Each cycle will execute different codes in the component's life cycle hook function stage.

Vue3 Basic Tutorial Creation Cycle

The creation cycle is one of the most important cycles for components in Vue.js. In the initial stage, Vue will create component instances and initialize related data.

In the creation cycle, Vue provides the following 6 life cycle functions:

1. beforeCreate()
2. created()
3. beforeMount( )
4. mounted()
5. beforeUpdate()
6. updated()

beforeCreate()

In the creation cycle In the first phase, Vue will call the component's beforeCreate() function. At this stage, the component's data, calculated properties, methods, etc. have not yet been mounted to the component instance.

This stage is very suitable for operations such as obtaining global data and initializing non-responsive data.

created()

Next, Vue will call the component’s created() function. At this stage, the component's data, computed properties, and methods have been created and can be used directly.

This stage is very suitable for asynchronous data acquisition, initializing some temporary data, initializing output data and other operations.

beforeMount()

After the component is created, Vue will call the beforeMount() function. At this stage, the component's template has been compiled but not rendered into the DOM tree.

This stage is very suitable for operations such as modifying component templates and modifying some temporary data.

mounted()

After the template is compiled and rendered to the DOM tree, Vue will call the mounted() function. At this stage, the component has been fully initialized and can be accessed in the DOM.

This stage is very suitable for initializing plug-ins, event listeners and other operations.

beforeUpdate()

After mounted(), Vue will update the state of the component through data binding. At this stage, Vue calls the beforeUpdate() function.

This stage is very suitable for operations such as monitoring status changes and preparing to update data.

updated()

After beforeUpdate(), Vue will update the components in the DOM tree. When the update is complete, Vue calls the updated() function.

This stage is very suitable for operations such as DOM operations and manual triggering of sub-component updates.

Vue3 Basic Tutorial Update Cycle

In the Vue component, when the data or state of the component changes, Vue will trigger the update cycle. In the update cycle, Vue provides 2 hook functions:

1. beforeUpdate()
2. updated()

Vue3 Basic Tutorial Destruction Cycle

When a Vue component is destroyed, Vue will call the component's destroyed() function. At this stage, the component has been destroyed and the associated DOM has been removed.

This stage is very suitable for operations such as clearing timers, canceling event listeners, and releasing resources.

Conclusion

Vue lifecycle hooks are an important part of the Vue.js concept and provide a convenient way to execute code at different stages. In the Vue3 Basics tutorial, we took an in-depth look at Vue lifecycle hooks and their usage.

In actual development, reasonable use of life cycle hooks can make applications more optimized and efficient. It is recommended that developers make full use of Vue life cycle hooks when writing Vue applications and add appropriate code at different stages to achieve the best performance and user experience.

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