quasar/src/utils/EventBus/EventBus.js

Build high-performance VueJS user interfaces (SPA, PWA, SSR, Mobile and Desktop) in record time

/**
 * Forked from tiny-emitter
 * Copyright (c) 2017 Scott Corgan
 */

export default class EventBus {
  constructor () {
    this.__stack = {}
  }

  on (name, callback, ctx) {
    (this.__stack[ name ] || (this.__stack[ name ] = [])).push({
      fn: callback,
      ctx
    })

    return this // chainable
  }

  once (name, callback, ctx) {
    const listener = (...args) => {
      this.off(name, listener)
      callback.apply(ctx, args)
    }

    listener.__callback = callback
    return this.on(name, listener, ctx) // chainable
  }

  emit (name) {
    const list = this.__stack[ name ]

    if (list !== void 0) {
      const params = [].slice.call(arguments, 1)
      list.forEach(entry => {
        entry.fn.apply(entry.ctx, params)
      })
    }

    return this // chainable
  }

  off (name, callback) {
    const list = this.__stack[ name ]

    if (list === void 0) {
      return this // chainable
    }

    if (callback === void 0) {
      delete this.__stack[ name ]
      return this // chainable
    }

    const liveEvents = list.filter(
      entry => entry.fn !== callback && entry.fn.__callback !== callback
    )

    if (liveEvents.length !== 0) {
      this.__stack[ name ] = liveEvents
    }
    else {
      delete this.__stack[ name ]
    }

    return this // chainable
  }
}