EventEmitter

An implementation of EventEmitter for browsers which can use an Object as the event type.

Installation

$ npm i @lvchengbin/event-emitter --save

If you want to invoke the code to browers with <script> tag, please use event-emitter.js. For old browsers not support ES5 syntax, please use event-emitter.bc.js.

Usage

import EventEmitter from '@lvchengbin/event-emitter';

const em = new EventEmitter();

const handler = () => {
    // some code...
};

em.on( 'event', handler );
em.emit( 'event', ...args );
em.removeListener( 'event', handler );

import EventEmitter from '@lvchengbin/event-emitter';

class A extends EventEmitter {
    constructor() {
        super();

        this.on( 'xxx', () => {
            // some code...
        } );
    }
}

new A().on( 'msg', () => {
} );

Using an Object as the event type.

const em = new EventEmitter();

const func = {};

em.on( func, () => {
} );

Methods

• on( evt, handler )

  Start to listen to an event type.

• once( evt, handler )

  Start to listen to an event type only once, then the listener will be removed.

• removeListener( evt, handler )

  Remove lister of an event type to stop listening it.

• emit( evt, ...args )

  To trigger an event

• removeAllListeners( rule )

  To remove listeners with a rule:

  • if the rule is a string, to remove all events with event type same as the rule
  • if the rule is a regexp, to remove all events match the regexp
  • if the rule is a function, to execute the function with passing an argument which is each event type, if the function returns true, all listeners of that event type will be removed.

  em.removeAllListeners( type => {
      if( /^ss/i.test( type ) ) {
          return true;
      }
  } );
  em.removeAllListeners( 'click' );
  em.removeAllListeners( /click/i );

• alias( alias, existsMethod )

  To set alias for a existing method, for example:

  class EC extends EventEmitter {
      constructor() {
          super();
          this.alias( '$on', 'on' );
      }
  }