How is the vue hook function implemented

Vue implements hook functions using a combination API and proxy trick. By setting functions and responsive data, Vue intercepts and calls hook functions when accessing component instance properties, allowing developers to execute custom logic at the lifecycle stage.

Implementation of Vue hook function

Vue hook functions are predefined functions that allow developers to execute custom logic at specific stages of the component life cycle. Vue implements these hook functions by using composition API and proxy tricks.

composition API

composition API extracts the component's responsive data and methods from <script></script> block into a standalone function called setup() . In the setup() function, Vue uses ref() and reactive() functions to create reactive data, and uses onMounted() , onUpdated() and other functions to declare the hook function.

proxy skills

Vue uses proxy tricks to intercept access to component instance objects. When accessing a property on a component instance object, proxy checks whether a hook function with the same name as this property is defined. If a hook function is defined, the hook function is called before accessing the property.

Specific implementation

When setup() function is called, Vue creates a component instance object. It then creates a proxy object to intercept access to the component instance object properties.

When accessing a property on the component instance object, the proxy object checks whether the hook function with the same name is declared in setup() function.

If a hook function is declared, the hook function is called before accessing the property. Hook functions can perform custom logic, such as making API requests, updating status, or performing other operations.

If the hook function is not declared, the proxy object returns the property value directly, just like a regular object.

By using composition API and proxy tricks, Vue can provide convenient and scalable hook function mechanisms at specific stages of the component life cycle.

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