Function isEventSupported

code/composition/public/app.js:3855–3870

* Checks if an event is supported in the current execution environment. * * NOTE: This will not work correctly for non-generic events such as `change`, * `reset`, `load`, `error`, and `select`. * * Borrows from Modernizr. * * @param {string} eventNameSuffix Event name, e.g. "click". * @param

(eventNameSuffix, capture)

 * @license Modernizr 3.0.0pre (Custom Build) | MIT
 */
function isEventSupported(eventNameSuffix, capture) {
  if (!ExecutionEnvironment.canUseDOM || capture && !('addEventListener' in document)) {
    return false;
  }

  var eventName = 'on' + eventNameSuffix;
  var isSupported = eventName in document;

  if (!isSupported) {
    var element = document.createElement('div');
    element.setAttribute(eventName, 'return;');
    isSupported = typeof element[eventName] === 'function';
  }

  return isSupported;
}

function isCheckable(elem) {
  var type = elem.type;