元素拖放

            // 获取节点
            var block = document.getElementById("right");
            var oW, oH;
            // 绑定touchstart事件
            block.addEventListener("touchstart", function (e) {
                var touches = e.touches[0];
                oW = touches.clientX - block.offsetLeft;
                oH = touches.clientY - block.offsetTop;
                //阻止页面的滑动默认事件
                document.addEventListener("touchmove", defaultEvent(event), false);
            }, false);
            block.addEventListener("touchmove", function (e) {
                var touches = e.touches[0];
                var oLeft = touches.clientX - oW;
                var oTop = touches.clientY - oH;
                if (oLeft < 0) {
                    oLeft = 0;
                } else if (oLeft > document.documentElement.clientWidth - block.offsetWidth) {
                    oLeft = (document.documentElement.clientWidth - block.offsetWidth);
                }
                block.style.left = oLeft + "px";
                block.style.top = oTop + "px";
            }, false);
            block.addEventListener("touchend", function () {
                document.removeEventListener("touchmove", defaultEvent(event), false);
            }, false);
            function defaultEvent(event) {
                event.preventDefault();
            };