TapCall

A simple tapable like hook module for plugins, which is friendly for typescript user.

中文文档 | The Chinese Document

Installation

npm install tapcall

Usage

All Hook constructors take one argument, which is the hook's name.

import { SyncHook } from 'tapcall';
const hook = new SyncHook('some-hook-name');

You can set the generic type of the hook if you are using typescript:

const hook = new SyncHook<[string, number], string>('some-hook-name');

Or you can use tuple labels for better readability:

const hook = new SyncHook<[arg1: string, arg2: number], string>('some-hook-name');

The best practice is to expose all hooks of a class in a hooks property:

class Cat {
  constructor() {
    this.hooks = {
      A: new SyncHook<[a: string]>(),
      B: new SyncHook<[b: number]>(),
    };
  }

  /* ... */
}

Other people can now use these hooks:

const cat = new Cat();

// Use the tap method to add a callback
cat.hooks.A.tap('some-plugin-name', (a) => console.log(a));

It's required to pass a name to identify the plugin.

The class declaring these hooks need to call them:

class Cat {
  /**
  * You won't get returned value from SyncHook or AsyncParallelHook,
  * to do that, use SyncWaterfallHook and AsyncSeriesWaterfallHook respectively
  **/

	setA(a: string) {
		// following call returns undefined even when you returned values
		this.hooks.A.call(a);
	}
}

API

All Hook class has the following methods.

tap(option, callback)

Register a callback to the hook.

• option: string | object
  • option.name: string, the name of the callback
  • option.stage?: number, the stage of the callback
  • option.before?: string | string[], the name of the callback before which the new callback will be inserted
• callback: function, the callback to be registered
  • args: the arguments passed to the callback, which is the same as the first generic type of the hook
  • return: the returned value of the callback, which is the same as the second generic type of the hook

call(...args)

Call all callbacks registered to the hook. The return value is determined by the hook type.

• args: the arguments passed to the callback, which is the same as the generic type of the hook

clear(callbacks)

Clear specify callbacks registered to the hook.

• callbacks: string | string[] | function | function[], the callbacks(or names) to be cleared

clearAll()

Clear all callbacks registered to the hook.

Hook Types

SyncHook

SyncHook is a synchronous hook. It calls all callbacks registered to the hook in order. If an error occurs when executing a callback, it will end early and throw a custom error.

The return value of the call method is undefined.

SyncBailHook

SyncBailHook is a synchronous hook. It calls all callbacks registered to the hook in order. If an error occurs when executing a callback, it will end early and throw a custom error. If a callback returns a value(except undefined), it will end early and return the value.

The return value of the call method is the returned value of the last executed callback.

SyncLoopHook

SyncLoopHook is a synchronous hook. It calls all callbacks registered to the hook in order. If an error occurs when executing a callback, it will end early and throw a custom error. Each callback will be called multiple times until it returns undefined, then it will call the next callback.

The return value of the call method is undefined.

SyncWaterfallHook

SyncWaterfallHook is a synchronous hook. It calls all callbacks registered to the hook in order. If an error occurs when executing a callback, it will end early and throw a custom error. The return value of a callback will be passed to the next callback.

The return value of the call method is the returned value of the last callback.

AsyncParallelHook

AsyncParallelHook is an asynchronous hook. It calls all callbacks registered to the hook in parallel.

The call method returns a promise, which resolves undefined. If a callback occurs an error or rejects a promise, it will end early and reject the promise with a custom error.

AsyncParallelBailHook

AsyncParallelBailHook is an asynchronous hook. It calls all callbacks registered to the hook in parallel.

The call method returns a promise, which resolves the first NOT undefined value or rejects an error(which will be wrapped in a custom error) of the callbacks.

AsyncSeriesHook

AsyncSeriesHook is an asynchronous hook. It calls all callbacks registered to the hook in order. If a callback occurs an error or rejects a promise, it will end early and reject the promise with a custom error.

The call method returns a promise, which resolves undefined.

AsyncSeriesBailHook

AsyncSeriesBailHook is an asynchronous hook. It calls all callbacks registered to the hook in order. If a callback occurs an error or rejects a promise, it will end early and reject the promise with a custom error. If a callback returns a value(except undefined), it will end early and resolve the promise with the value.

The call method returns a promise, which resolves the returned value of the last executed callback.

AsyncSeriesLoopHook

AsyncSeriesLoopHook is an asynchronous hook. It calls all callbacks registered to the hook in order. If a callback occurs an error or rejects a promise, it will end early and reject the promise with a custom error. Each callback will be called multiple times until it returns undefined, then it will call the next callback.

The call method returns a promise, which resolves undefined.

AsyncSeriesWaterfallHook

AsyncSeriesWaterfallHook is an asynchronous hook. It calls all callbacks registered to the hook in order. If a callback occurs an error or rejects a promise, it will end early and reject the promise with a custom error. The return value of a callback will be passed to the next callback.

The call method returns a promise, which resolves the returned value of the last callback.

Custom Error

When an error occurs, a custom error will be thrown or rejected. The error has the following properties:

• message: string, the error message
• type: string, the error occurred type
• hook: string, the name of the hook
• receiver: string, the name of the receiver
• stack: string, the original error stack trace