dom-helpers/esm/addEventListener.js

tiny modular DOM lib for ie9+

/* eslint-disable no-return-assign */
import canUseDOM from './canUseDOM';
export var optionsSupported = false;
export var onceSupported = false;

try {
  var options = {
    get passive() {
      return optionsSupported = true;
    },

    get once() {
      // eslint-disable-next-line no-multi-assign
      return onceSupported = optionsSupported = true;
    }

  };

  if (canUseDOM) {
    window.addEventListener('test', options, options);
    window.removeEventListener('test', options, true);
  }
} catch (e) {
  /* */
}

/**
 * An `addEventListener` ponyfill, supports the `once` option
 */
function addEventListener(node, eventName, handler, options) {
  if (options && typeof options !== 'boolean' && !onceSupported) {
    var once = options.once,
        capture = options.capture;
    var wrappedHandler = handler;

    if (!onceSupported && once) {
      wrappedHandler = handler.__once || function onceHandler(event) {
        this.removeEventListener(eventName, onceHandler, capture);
        handler.call(this, event);
      };

      handler.__once = wrappedHandler;
    }

    node.addEventListener(eventName, wrappedHandler, optionsSupported ? options : capture);
  }

  node.addEventListener(eventName, handler, options);
}

export default addEventListener;