unjs/hookable

🪝 Awaitable Hooks

Hookable

Awaitable hooks system.

Install

Using yarn:

yarn add hookable

Using npm:

npm install hookable

Usage

Method A: Create a hookable instance:

import { createHooks } from 'hookable'

// Create a hookable instance
const hooks = createHooks()

// Hook on 'hello'
hooks.hook('hello', () => { console.log('Hello World' )})

// Call 'hello' hook
hooks.callHook('hello')

Method B: Extend your base class from Hookable:

import { Hookable } from 'hookable'

export default class FooLib extends Hookable {
  constructor() {
    // Call to parent to initialize
    super()
    // Initialize Hookable with custom logger
    // super(consola)
  }

  async someFunction() {
    // Call and wait for `hook1` hooks (if any) sequential
    await this.callHook('hook1')
  }
}

Inside plugins, register for any hook:

const lib = new FooLib()

// Register a handler for `hook2`
lib.hook('hook2', async () => { /* ... */ })

// Register multiply handlers at once
lib.addHooks({
  hook1: async () => { /* ... */ },
  hook2: [ /* can be also an array */ ]
})

Unregistering hooks:

const lib = new FooLib()

const hook0 = async () => { /* ... */ }
const hook1 = async () => { /* ... */ }
const hook2 = async () => { /* ... */ }

// The hook() method returns an "unregister" function
const unregisterHook0 = lib.hook('hook0', hook0)
const unregisterHooks1and2 = lib.addHooks({ hook1, hook2 })

/* ... */

unregisterHook0()
unregisterHooks1and2()

// or

lib.removeHooks({ hook0, hook1 })
lib.removeHook('hook2', hook2)

Triggering a hook handler once:

const lib = new FooLib()

const unregister = lib.hook('hook0', async () => {
  // Unregister as soon as the hook is executed
  unregister()

  /* ... */
})

Hookable class

constructor()

hook (name, fn)

Register a handler for a specific hook. fn must be a function.

Returns an unregister function that, when called, will remove the registered handler.

hookOnce (name, fn)

Similar to hook but unregisters hook once called.

Returns an unregister function that, when called, will remove the registered handler before first call.

addHooks(configHooks)

Flatten and register hooks object.

Example:

hookable.addHooks({
  test: {
    before: () => {},
    after: () => {}
  }
})

This registers test:before and test:after hooks at bulk.

Returns an unregister function that, when called, will remove all the registered handlers.

async callHook (name, ...args)

Used by class itself to sequentially call handlers of a specific hook.

callHookWith (name, callerFn)

If you need custom control over how hooks are called, you can provide a custom function that will receive an array of handlers of a specific hook.

callerFn if a callback function that accepts two arguments, hooks and args:

• hooks: Array of user hooks to be called
• args: Array of arguments that should be passed each time calling a hook

deprecateHook (old, name)

Deprecate hook called old in favor of name hook.

deprecateHooks (deprecatedHooks)

Deprecate all hooks from an object (keys are old and values or newer ones).

removeHook (name, fn)

Remove a particular hook handler, if the fn handler is present.

removeHooks (configHooks)

Remove multiple hook handlers.

Example:

const handler = async () => { /* ... */ }

hookable.hook('test:before', handler)
hookable.addHooks({ test: { after: handler } })

// ...

hookable.removeHooks({
  test: {
    before: handler,
    after: handler
  }
})

removeAllHooks

Remove all hook handlers.

beforeEach (syncCallback)

Registers a (sync) callback to be called before each hook is being called.

hookable.beforeEach((event) => { console.log(`${event.name} hook is being called with ${event.args}`)}`)
hookable.hook('test', () => { console.log('running test hook') })

// test hook is being called with []
// running test hook
await hookable.callHook('test')

afterEach (syncCallback)

Registers a (sync) callback to be called after each hook is being called.

hookable.afterEach((event) => { console.log(`${event.name} hook called with ${event.args}`)}`)
hookable.hook('test', () => { console.log('running test hook') })

// running test hook
// test hook called with []
await hookable.callHook('test')

createDebugger

Automatically logs each hook that is called and how long it takes to run.

const debug = hookable.createDebugger(hooks, { tag: 'something' })

hooks.callHook('some-hook', 'some-arg')
// [something] some-hook: 0.21ms

debug.close()

Migration

From 4.x to 5.x

• Type checking improved. You can use Hookable<T> or createHooks<T>() to provide types interface (c2e1e22)
• We no longer provide an IE11 compatible umd build. Instead, you should use an ESM-aware bundler such as webpack or rollup to transpile if needed.
• Logger param is dropped. We use console.warn by default for deprecated hooks.
• Package now uses named exports. You should import { Hookable } instead of Hookable or use new createHooks util
• mergeHooks util is exported standalone. You should replace Hookable.mergeHooks and this.mergeHooks with new { mergeHooks } export
• In versions < 5.0.0 when using callHook if an error happened by one of the hook callbacks, we was handling errors globally and call global error hook + console.error instead and resolve callHook promise! This sometimes makes confusing behavior when we think code worked but it didn't. v5 introduced a breaking change that when a hook throws an error, callHook also rejects instead of a global error event. This means you should be careful to handle all errors when using callHook now.

Credits

Extracted from Nuxt hooks system originally introduced by Sébastien Chopin

Thanks to Joe Paice for donating hookable package name.

License

MIT - Made with 💖