通过fastclick源码分析彻底解决tap“点透”(2)

  layer.addEventListener('touchmove', this.onTouchMove, false);
  layer.addEventListener('touchend', this.onTouchEnd, false);
  layer.addEventListener('touchcancel', this.onTouchCancel, false);
 
  if (!Event.prototype.stopImmediatePropagation) {
   layer.removeEventListener = function(type, callback, capture) {
    var rmv = Node.prototype.removeEventListener;
    if (type === 'click') {
     rmv.call(layer, type, callback.hijacked || callback, capture);
    } else {
     rmv.call(layer, type, callback, capture);
    }
   };
 
   layer.addEventListener = function(type, callback, capture) {
    var adv = Node.prototype.addEventListener;
    if (type === 'click') {
     adv.call(layer, type, callback.hijacked || (callback.hijacked = function(event) {
      if (!event.propagationStopped) {
       callback(event);
      }
     }), capture);
    } else {
     adv.call(layer, type, callback, capture);
    }
   };
  }
  if (typeof layer.onclick === 'function') {
   oldOnClick = layer.onclick;
   layer.addEventListener('click', function(event) {
 oldOnClick(event);
 }, false);
 layer.onclick = null;
}
}

if (!layer || !layer.nodeType) {
throw new TypeError('Layer must be a document node');
}

 FastClick.notNeeded = function(layer) {
  'use strict';
  var metaViewport;
  if (typeof window.ontouchstart === 'undefined') {
   return true;
  }
  if ((/Chrome\/[0-9]+/).test(navigator.userAgent)) {
   if (FastClick.prototype.deviceIsAndroid) {
    metaViewport = document.querySelector('meta[name=viewport]');
    if (metaViewport && metaViewport.content.indexOf('user-scalable=no') !== -1) {
     return true;
    }
   } else {
    return true;
   }
  }
  if (layer.style.msTouchAction === 'none') {
   return true;
  }
  return false;