Allow

callback-sequence.js

class CallbackSequence extends Function {
  constructor() {
    super();
    this.callbacks = {};
    return new Proxy(this, {
      apply: (target, thisArg, argumentsList) => {
        this.__call__();
      }
    });
  }

  __call__ = () => {
    for (let [key, cb] of Object.entries(this.callbacks)) {
      cb();
    }
  };

  add = (key, callback) => {
    this.callbacks[key] = callback;
  };

  remove = (key) => {
    delete this.callbacks[key];
  };

}

/*
 * If you want to call multiple functions when a event, for example, 'window.resize' happens, do:
 * window.onresize = windows.onresize || new CallbackSequence();
 * window.onresize.add("1", () => { console.log ("We wish you a merry Christmas. "); })
 * window.onresize.add("2", () => { console.log ("We wish you a merry Christmas. "); })
 * window.onresize.add("3", () => { console.log ("And happy new year! "); })
 */