原生JS实现弹出窗口的拖拽（直接copy可用）

function DivMove(divId, h2Tag) {
        var oWin = document.getElementById(divId);
        var oH2 = oWin.getElementsByTagName(h2Tag)[0];
        var bDrag = false;
        var disX = disY = 0;
        oH2.onmousedown = function (event) {
            var event = event || window.event;
            bDrag = true;
            disX = event.clientX - oWin.offsetLeft;
            disY = event.clientY - oWin.offsetTop;
            this.setCapture && this.setCapture();
            return false
        };
        document.onmousemove = function (event) {
            if (!bDrag) return;
            var event = event || window.event;
            var iL = event.clientX - disX;
            var iT = event.clientY - disY;
            var maxL = document.documentElement.clientWidth - oWin.offsetWidth;
            var maxT = document.documentElement.clientHeight - oWin.offsetHeight;
            iL = iL < 0 ? 0 : iL;
            iL = iL > maxL ? maxL : iL;
            iT = iT < 0 ? 0 : iT;
            iT = iT > maxT ? maxT : iT;

            oWin.style.marginTop = oWin.style.marginLeft = 0;
            oWin.style.left = iL + "px";
            oWin.style.top = iT + "px";
            return false
        };
        document.onmouseup = window.onblur = oH2.onlosecapture = function () {
            bDrag = false;
            oH2.releaseCapture && oH2.releaseCapture();
        };
    }