用手势来决定放大缩小 各路大神帮我指点一下代码

Question

 var holdFlag = false,            id_scale = document.getElementById("scale"),    moveFlag = false,    holdTimestamp = 0,    touches = [],    size = 0.01,    _scale = 1,        touch1X, touch2X;        var touchArea = document.querySelector('#touchArea');        touchArea.addEventListener('touchstart', function (event) {            event.preventDefault();            holdFlag = true;            holdTimestamp = (new Date()).getTime();            touches = event.touches;            //alert(1)            //console.log(1)            //alert(touches.length)            //touch1X = touches[0].clientX;            //if (touches.length == 2) {            //touch1X = touches[0].clientX;            // touch2X = touches[1].clientX;            // }        }, false);        touchArea.addEventListener('touchmove', function (event) {            event.preventDefault();            var _touches = event.touches;            moveFlag = true;                       if (touches.length == 2) {                if (holdFlag) {                    touch1X = touches[0].clientX;                     touch2X = touches[1].clientX;                    holdFlag = false;                }                if ((touch1X > _touches[0].clientX && touch2X < _touches[1].clientX) || (touch1X == _touches[0].clientX && touch2X < _touches[1].clientX) || (touch1X > _touches[0].clientX && touch2X == _touches[1].clientX)) {//放大                    _scale = _scale + size;                    //alert(2 + " " + _scale)                    console.log(2)                    if (_scale < 2 && _scale > 1)                        id_scale.style.transform = 'scale(' + _scale + ')';                }                else if ((touch1X < _touches[0].clientX && touch2X > _touches[1].clientX) || (touch1X == _touches[0].clientX && touch2X > _touches[1].clientX) || (touch1X < _touches[0].clientX && touch2X == _touches[1].clientX)) {//缩小                    _scale = _scale - size;                   // alert(3 + " " + _scale)                    console.log(3)                    if (_scale > 1 && _scale < 2)                        id_scale.style.transform = 'scale(' + _scale + ')';                }            }                   });不知道最后两个判断不知道问题出在哪里了 最上面的明明是代表手势撑开 然后有时候会放大有时候会缩小