javascript - 滑动删除javascript

Question

我正在开发一个函数，当您向左滑动时，该函数将删除 div...

这是一个我想在滑动时删除的 div:

<div class="listItem">Stuff here</div>

我有 javascript 来确定我通过使用 touchstart 和 touchend 事件监听器在页面上滑动的位置。

我创建了一个函数来删除该项目:

function swipeLeft(){
     //delete item
}

我正在确定我像这样滑动的位置:

var touchobj = e.changedTouches[0];
dist = touchobj.pageX - startX 

现在可以删除包含此信息的 div 吗？

Answer 1

是的，您只需计算 div 大小和滑动距离之间的增量。

这是通用滑动模式检测的一个很好的示例:

http://www.javascriptkit.com/javatutors/touchevents2.shtml

代码:

function swipedetect(el, callback){

    var touchsurface = el,
    swipedir,
    startX,
    startY,
    distX,
    distY,
    threshold = 150, //required min distance traveled to be considered swipe
    restraint = 100, // maximum distance allowed at the same time in perpendicular direction
    allowedTime = 300, // maximum time allowed to travel that distance
    elapsedTime,
    startTime,
    handleswipe = callback || function(swipedir){}

    touchsurface.addEventListener('touchstart', function(e){
        var touchobj = e.changedTouches[0]
        swipedir = 'none'
        dist = 0
        startX = touchobj.pageX
        startY = touchobj.pageY
        startTime = new Date().getTime() // record time when finger first makes contact with surface
        e.preventDefault()
    }, false)

    touchsurface.addEventListener('touchmove', function(e){
        e.preventDefault() // prevent scrolling when inside DIV
    }, false)

    touchsurface.addEventListener('touchend', function(e){
        var touchobj = e.changedTouches[0]
        distX = touchobj.pageX - startX // get horizontal dist traveled by finger while in contact with surface
        distY = touchobj.pageY - startY // get vertical dist traveled by finger while in contact with surface
        elapsedTime = new Date().getTime() - startTime // get time elapsed
        if (elapsedTime <= allowedTime){ // first condition for awipe met
            if (Math.abs(distX) >= threshold && Math.abs(distY) <= restraint){ // 2nd condition for horizontal swipe met
                swipedir = (distX < 0)? 'left' : 'right' // if dist traveled is negative, it indicates left swipe
            }
            else if (Math.abs(distY) >= threshold && Math.abs(distX) <= restraint){ // 2nd condition for vertical swipe met
                swipedir = (distY < 0)? 'up' : 'down' // if dist traveled is negative, it indicates up swipe
            }
        }
        handleswipe(swipedir)
        e.preventDefault()
    }, false)
}

//USAGE:
/*
var el = document.getElementById('someel')
swipedetect(el, function(swipedir){
    swipedir contains either "none", "left", "right", "top", or "down"
    if (swipedir =='left')
        alert('You just swiped left!')
})
*/

您所做的就是根据需要调整阈值。一旦检测到，您只需从 DOM 中删除该 div 即可。