overleaf/services/web/frontend/js/utils/EventEmitter.js

/* eslint-disable
    camelcase,
    max-len,
    no-return-assign,
    no-unused-vars,
*/
// TODO: This file was created by bulk-decaffeinate.
// Fix any style issues and re-enable lint.
/*
 * decaffeinate suggestions:
 * DS101: Remove unnecessary use of Array.from
 * DS102: Remove unnecessary code created because of implicit returns
 * DS207: Consider shorter variations of null checks
 * Full docs: https://github.com/decaffeinate/decaffeinate/blob/master/docs/suggestions.md
 */
// Simple event emitter implementation, but has a slightly unusual API for
// removing specific listeners. If a specific listener needs to be removed
// (instead of all listeners), then it needs to use a "namespace":
// Create a listener on the foo event with bar namespace: .on 'foo.bar'
// Trigger all events for the foo event (including namespaces): .trigger 'foo'
// Remove all listeners for the foo event (including namespaces): .off 'foo'
// Remove a listener for the foo event with the bar namespace: .off 'foo.bar'

export default class EventEmitter {
  on(event, callback) {
    let namespace
    if (!this.events) {
      this.events = {}
    }
    ;[event, namespace] = Array.from(event.split('.'))
    if (!this.events[event]) {
      this.events[event] = []
    }
    return this.events[event].push({
      callback,
      namespace,
    })
  }

  off(event) {
    if (!this.events) {
      this.events = {}
    }
    if (event != null) {
      let namespace
      ;[event, namespace] = Array.from(event.split('.'))
      if (namespace == null) {
        // Clear all listeners for event
        return delete this.events[event]
      } else {
        // Clear only namespaced listeners
        const remaining_events = []
        for (const callback of Array.from(this.events[event] || [])) {
          if (callback.namespace !== namespace) {
            remaining_events.push(callback)
          }
        }
        return (this.events[event] = remaining_events)
      }
    } else {
      // Remove all listeners
      return (this.events = {})
    }
  }

  trigger(event, ...args) {
    if (!this.events) {
      this.events = {}
    }
    return Array.from(this.events[event] || []).map(callback =>
      callback.callback(...Array.from(args || []))
    )
  }

  emit(...args) {
    return this.trigger(...Array.from(args || []))
  }
}