devdocs/assets/javascripts/lib/events.js

// TODO: This file was created by bulk-decaffeinate.
// Sanity-check the conversion and remove this comment.
/*
 * decaffeinate suggestions:
 * DS101: Remove unnecessary use of Array.from
 * DS102: Remove unnecessary code created because of implicit returns
 * DS104: Avoid inline assignments
 * DS207: Consider shorter variations of null checks
 * DS208: Avoid top-level this
 * Full docs: https://github.com/decaffeinate/decaffeinate/blob/main/docs/suggestions.md
 */
class Events {
  on(event, callback) {
    if (event.indexOf(" ") >= 0) {
      for (var name of Array.from(event.split(" "))) {
        this.on(name, callback);
      }
    } else {
      let base;
      ((base =
        this._callbacks != null ? this._callbacks : (this._callbacks = {}))[
        event
      ] != null
        ? base[event]
        : (base[event] = [])
      ).push(callback);
    }
    return this;
  }

  off(event, callback) {
    let callbacks, index;
    if (event.indexOf(" ") >= 0) {
      for (var name of Array.from(event.split(" "))) {
        this.off(name, callback);
      }
    } else if (
      (callbacks =
        this._callbacks != null ? this._callbacks[event] : undefined) &&
      (index = callbacks.indexOf(callback)) >= 0
    ) {
      callbacks.splice(index, 1);
      if (!callbacks.length) {
        delete this._callbacks[event];
      }
    }
    return this;
  }

  trigger(event, ...args) {
    this.eventInProgress = { name: event, args };
    const callbacks = this._callbacks?.[event];
    if (callbacks) {
      for (let callback of Array.from(callbacks.slice(0))) {
        if (typeof callback === "function") {
          callback(...args);
        }
      }
    }
    this.eventInProgress = null;
    if (event !== "all") {
      this.trigger("all", event, ...Array.from(args));
    }
    return this;
  }

  removeEvent(event) {
    if (this._callbacks != null) {
      for (var name of Array.from(event.split(" "))) {
        delete this._callbacks[name];
      }
    }
    return this;
  }
}