Zepto tap 穿透bug、解决移动端点击穿透问题

　　当两个层重叠在一起时，或是有个弹窗，使用Zepto的tap事件时，点击上面的一层时会触发下面一层的事件，特别是底层如果是input框时，必“穿 透”，“google”说原因是“tap事件实际上是在冒泡到body上时才触发”，也就是Zepto的tap事件是绑定在document上的，所以会导致，这个还未求证。

如下图， 当点击关闭按钮，如果下面有商品a链接，则会穿透（关闭的同时，触发了链接）；

 

 

现象原因：

　　zepto的tap通过兼听绑定在document上的touch事件来完成tap事件的模拟的,及tap事件是冒泡到document上触发的，再点击完成时的tap事件(touchstart\touchend)需要冒泡到document上才会触发，而在冒泡到document之前，用 户手的接触屏幕(touchstart)和离开屏幕(touchend)是会触发click事件的,因为click事件有延迟触发(这就是为什么移动端不 用click而用tap的原因)(大概是300ms,为了实现safari的双击事件的设计)，所以在执行完tap事件之后，弹出来的选择组件马 上就隐藏了，此时click事件还在延迟的300ms之中，当300ms到来的时候，click到的其实不是完成而是隐藏之后的下方的元素，如果正下方的 元素绑定的有click事件此时便会触发，如果没有绑定click事件的话就当没click，但是正下方的是input输入框(或者select选择框或 者单选复选框)，点击默认聚焦而弹出输入键盘，也就出现了上面的点透现象。

解决方法如下：

1、使用github上有一个叫做fastclick的库；

2、监听touchend事件，并在事件中使用preventDefault()阻止冒泡；

$(".js-egg-close").on("touchend", function(e) { //这里使用touchstart事件也是可以的，
    e.preventDefault();
    $('.sec_dlg_eggs').remove();
    $(".eggs_bg").remove();
});

3、使用css3的pointer-events=true,pointer-events=none切换来实现；

4.延迟一定的时间来处理事件。与jquery的动画(fadeIn()，fadeOut())等配合感觉良好；

$(id).fadeIn(300);

5.如果还不奏效，终极解决方案是用click提代tap；

设置点击事件为_tap：

_tap = touchend in document ? "touchend":"click"；

这样在执行的过程中就可以直接调用div.on(_tap, function(){}) 

下面我们贴下zepto.1.1.6 tap事件的源码：

;(function($){
    var touch = {},
        touchTimeout, tapTimeout, swipeTimeout, longTapTimeout,
        longTapDelay = 750,
        gesture
  　 
　　 // 判断左右上下滑动的方向
    function swipeDirection(x1, x2, y1, y2) {
　　　　　// Math.abs()：返回数字的绝对值
        return Math.abs(x1 - x2) >= Math.abs(y1 - y2) ? (x1 - x2 > 0 ? 'Left' : 'Right') : (y1 - y2 > 0 ? 'Up' : 'Down')
    }  

    function longTap() {
        longTapTimeout = null
        if (touch.last) {
            touch.el.trigger('longTap')
            touch = {}
        }
    }  

    function cancelLongTap() {
        if (longTapTimeout) clearTimeout(longTapTimeout)
        longTapTimeout = null
    }  

    function cancelAll() {
        if (touchTimeout) clearTimeout(touchTimeout)
        if (tapTimeout) clearTimeout(tapTimeout)
        if (swipeTimeout) clearTimeout(swipeTimeout)
        if (longTapTimeout) clearTimeout(longTapTimeout)
        touchTimeout = tapTimeout = swipeTimeout = longTapTimeout = null
        touch = {}
    }  

    function isPrimaryTouch(event){
        return (event.pointerType == 'touch' ||  event.pointerType == event.MSPOINTER_TYPE_TOUCH) && event.isPrimary
    }  

    function isPointerEventType(e, type){
        return (e.type == 'pointer'+type || e.type.toLowerCase() == 'mspointer'+type)
    }  

    $(document).ready(function(){
        var now, delta, deltaX = 0, deltaY = 0, firstTouch, _isPointerType  

        if ('MSGesture' in window) {
            gesture = new MSGesture()
            gesture.target = document.body
        }  

        $(document)
            .bind('MSGestureEnd', function(e){
                var swipeDirectionFromVelocity =
                        e.velocityX > 1 ? 'Right' : e.velocityX < -1 ? 'Left' : e.velocityY > 1 ? 'Down' : e.velocityY < -1 ? 'Up' : null;
                if (swipeDirectionFromVelocity) {
                    touch.el.trigger('swipe')
                    touch.el.trigger('swipe'+ swipeDirectionFromVelocity)
                }
            })
            .on('touchstart MSPointerDown pointerdown', function(e){
                if((_isPointerType = isPointerEventType(e, 'down')) &&
                    !isPrimaryTouch(e)) return
                firstTouch = _isPointerType ? e : e.touches[0]
                if (e.touches && e.touches.length === 1 && touch.x2) {
                    // Clear out touch movement data if we have it sticking around
                    // This can occur if touchcancel doesn't fire due to preventDefault, etc.
                    touch.x2 = undefined
                    touch.y2 = undefined
                }
                now = Date.now()
                delta = now - (touch.last || now)
                touch.el = $('tagName' in firstTouch.target ?
                    firstTouch.target : firstTouch.target.parentNode)
                touchTimeout && clearTimeout(touchTimeout)
                touch.x1 = firstTouch.pageX
                touch.y1 = firstTouch.pageY
                if (delta > 0 && delta <= 250) touch.isDoubleTap = true
                touch.last = now
                longTapTimeout = setTimeout(longTap, longTapDelay)
                // adds the current touch contact for IE gesture recognition
                if (gesture && _isPointerType) gesture.addPointer(e.pointerId);
            })
            .on('touchmove MSPointerMove pointermove', function(e){
                if((_isPointerType = isPointerEventType(e, 'move')) &&
                    !isPrimaryTouch(e)) return
                firstTouch = _isPointerType ? e : e.touches[0]
                cancelLongTap()
                touch.x2 = firstTouch.pageX
                touch.y2 = firstTouch.pageY  

                deltaX += Math.abs(touch.x1 - touch.x2)
                deltaY += Math.abs(touch.y1 - touch.y2)
            })
            .on('touchend MSPointerUp pointerup', function(e){
                if((_isPointerType = isPointerEventType(e, 'up')) &&
                    !isPrimaryTouch(e)) return
                cancelLongTap()  

                // swipe
                if ((touch.x2 && Math.abs(touch.x1 - touch.x2) > 30) || (touch.y2 && Math.abs(touch.y1 - touch.y2) > 30))  

                    swipeTimeout = setTimeout(function() {
                        touch.el.trigger('swipe')
                        touch.el.trigger('swipe' + (swipeDirection(touch.x1, touch.x2, touch.y1, touch.y2)))
                        touch = {}
                    }, 0)  

                // normal tap
                else if ('last' in touch)
                // don't fire tap when delta position changed by more than 30 pixels,
                // for instance when moving to a point and back to origin
                    if (deltaX < 30 && deltaY < 30) {
                        // delay by one tick so we can cancel the 'tap' event if 'scroll' fires
                        // ('tap' fires before 'scroll')
                        tapTimeout = setTimeout(function() {  

                            // trigger universal 'tap' with the option to cancelTouch()
                            // (cancelTouch cancels processing of single vs double taps for faster 'tap' response)
                            var event = $.Event('tap')
                            event.cancelTouch = cancelAll
                            touch.el.trigger(event)  

                            // trigger double tap immediately
                            if (touch.isDoubleTap) {
                                if (touch.el) touch.el.trigger('doubleTap')
                                touch = {}
                            }  

                            // trigger single tap after 250ms of inactivity
                            else {
                                touchTimeout = setTimeout(function(){
                                    touchTimeout = null
                                    if (touch.el) touch.el.trigger('singleTap')
                                    touch = {}
                                }, 250)
                            }
                        }, 0)
                    } else {
                        touch = {}
                    }
                deltaX = deltaY = 0  

            })
            // when the browser window loses focus,
            // for example when a modal dialog is shown,
            // cancel all ongoing events
            .on('touchcancel MSPointerCancel pointercancel', cancelAll)  

        // scrolling the window indicates intention of the user
        // to scroll, not tap or swipe, so cancel all ongoing events
        $(window).on('scroll', cancelAll)
    })  

    ;['swipe', 'swipeLeft', 'swipeRight', 'swipeUp', 'swipeDown', 'doubleTap', 'tap', 'singleTap', 'longTap'].forEach(function(eventName){
        $.fn[eventName] = function(callback){
            return this.on(eventName, callback);
        }
    })
})(Zepto) 

 

。