js popup layer and can be dragged_javascript skills

<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>The layer pops up and can be dragged</title> <style> html,body{height:100%;overflow:hidden;} body,div,h2{margin:0;padding:0;} body{font:12px/1.5 Tahoma;} center{padding-top:10px;} button{cursor:pointer;} #overlay{position:absolute;top:0;left:0;width:100%;height:100%;background:#000;opacity:0.5;filter:alpha(opacity=50);display:none;} #win{position:absolute;top:50%;left:50%;width:400px;height:200px;background:#fff;border:4px solid #f90;margin:-102px 0 0 -202px;display:none;} h2{font-size:12px;height:18px;text-align:right;background:#FC0;border-bottom:3px solid #f90;padding:5px;cursor:move;} h2 span{color:#f90;cursor:pointer;background:#fff;border:1px solid #f90;padding:0 2px;} </style> <div id="overlay"> </div> <div id="win"> <h2> <span id="close"></span>×</h2> </div> <center> <button></button>Pop-up layer</center>
[Ctrl A select all Note: If you need to introduce external Js, you need to refresh to execute

]<script> window.onload = function () { var oWin = document.getElementById("win"); var oLay = document.getElementById("overlay"); var oBtn = document.getElementsByTagName("button")[0]; var oClose = document.getElementById("close"); var oH2 = oWin.getElementsByTagName("h2")[0]; var bDrag = false; var disX = disY = 0; oBtn.onclick = function () { oLay.style.display = "block"; oWin.style.display = "block" }; oClose.onclick = function () { oLay.style.display = "none"; oWin.style.display = "none" }; oClose.onmousedown = function (event) { (event || window.event).cancelBubble = true; }; 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(); }; }; </script>