livereload-js/src/customevents.js

const CustomEvents = {
  bind (element, eventName, handler) {
    if (element.addEventListener) {
      return element.addEventListener(eventName, handler, false);
    }

    if (element.attachEvent) {
      element[eventName] = 1;

      return element.attachEvent('onpropertychange', function (event) {
        if (event.propertyName === eventName) {
          return handler();
        }
      });
    }

    throw new Error(`Attempt to attach custom event ${eventName} to something which isn't a DOMElement`);
  },
  fire (element, eventName) {
    if (element.addEventListener) {
      const event = document.createEvent('HTMLEvents');

      event.initEvent(eventName, true, true);

      return document.dispatchEvent(event);
    } else if (element.attachEvent) {
      if (element[eventName]) {
        return element[eventName]++;
      }
    } else {
      throw new Error(`Attempt to fire custom event ${eventName} on something which isn't a DOMElement`);
    }
  }
};

exports.bind = CustomEvents.bind;
exports.fire = CustomEvents.fire;