What are the life cycle hook functions in Vue, and when are they triggered?

Vue is a JavaScript framework widely used in front-end development. It provides a series of life cycle hook functions. Developers can use these hook functions to operate components at specific times to achieve richer interactive effects and Function. The life cycle hook functions in Vue and their functions will be introduced in detail below.

Vue’s life cycle hook functions can be divided into three categories: creation phase, mounting phase and destruction phase. The following are the specific hook functions and their functions in each category:

1. Creation phase

In the creation phase, Vue will execute the following life cycle hook functions in sequence:

1. beforeCreate

When the instance is created, the data observation and event system has not yet been initialized. In the beforeCreate hook function, instance properties such as data and methods cannot be accessed. This stage is mainly suitable for some special initialization operations, such as adding custom properties and methods to the current instance or performing some asynchronous operations.

2. created

After the instance is created, the data observation and event system has been initialized. In the created hook function, you can access instance attributes such as data and methods. At this stage, the Vue instance has been created but has not yet been mounted on the page.

2. Mounting Phase

In the mounting phase, Vue will execute the following life cycle hook functions in sequence:

3. beforeMount

Before the instance is mounted, the DOM has not been generated. In the beforeMount hook function, you can perform some preparation work, such as adding styles to certain elements.

4. mounted

After the instance is mounted, the DOM has been generated and the Vue instance has been created. In the mounted hook function, you can access DOM elements and instance attributes such as data. This stage is mainly used to perform some DOM operations, such as using jQuery, calling third-party plug-ins, etc.

3. Destruction phase

In the destruction phase, Vue will execute the following life cycle hook functions in sequence:

5. beforeDestroy

In Called before the instance is destroyed. In the beforeDestroy hook function, you can perform some cleanup work, such as canceling timers, destroying subcomponents, etc.

6. destroyed

Called after the instance is destroyed. In the destroyed hook function, all data on the instance has been cleared and no longer exists in memory. This stage is mainly used to perform some aftermath work, such as disconnecting from the backend, canceling binding events, etc.

To sum up, Vue's life cycle hook functions are executed at different stages. Developers can use these hook functions to achieve various interactive effects and functions. In actual development, we can also use these hook functions reasonably based on business needs to improve the performance and maintainability of the application.

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