Exploring the FunctionDirective in Vue3

Question

Exploring the FunctionDirective in Vue3

In Vue3 Type Declaration, there is a definition for the Directive, which looks like this:

export declare type Directive<T = any, V = any> = ObjectDirective<T, V> | FunctionDirective<T, V>;

Most people are familiar with the ObjectDirective:

export declare interface ObjectDirective<T = any, V = any> {
    created?: DirectiveHook<T, null, V>;
    beforeMount?: DirectiveHook<T, null, V>;
    mounted?: DirectiveHook<T, null, V>;
    beforeUpdate?: DirectiveHook<T, VNode<any, T>, V>;
    updated?: DirectiveHook<T, VNode<any, T>, V>;
    beforeUnmount?: DirectiveHook<T, null, V>;
    unmounted?: DirectiveHook<T, null, V>;
    getSSRProps?: SSRDirectiveHook;
    deep?: boolean;
}

But what exactly is the FunctionDirective?

export declare type FunctionDirective<T = any, V = any> = DirectiveHook<T, any, V>;

export declare type DirectiveHook<T = any, Prev = VNode<any, T> | null, V = any> = (el: T, binding: DirectiveBinding<V>, vnode: VNode<any, T>, prevVNode: Prev) => void;

I have searched through the official documentation but couldn't find much information about it. Can anyone explain what this is and how to use it?

javascript vue.js vuejs3

Answer 1

Answer №1

There are a couple of ways to define a Vue directive - using object syntax, where you specify all the hooks that your directive is interested in, and functional syntax, where you provide a function that will be used for the mounted and updated hooks.

For example, declaring the directive like this:

const hook = (el, binding) => {
  // do something
}

app.directive('my-directive', hook)

...is equivalent to:

const hook = (el, binding) => {
  // do something
}

app.directive('my-directive', {
  mounted: hook,
  updated: hook,
})

Answer 2

There are a couple of ways to define a Vue directive - using object syntax, where you specify all the hooks that your directive is interested in, and functional syntax, where you provide a function that will be used for the mounted and updated hooks.

For example, declaring the directive like this:

const hook = (el, binding) => {
  // do something
}

app.directive('my-directive', hook)

...is equivalent to:

const hook = (el, binding) => {
  // do something
}

app.directive('my-directive', {
  mounted: hook,
  updated: hook,
})

Exploring the FunctionDirective in Vue3

Answer №1

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