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