js弹出div并显示遮罩层

//--------------------弹出层------------------- 
//popDivId:弹出层div的ID 
//dragDivId:用于拖动div的ID 
//isShowMask:是否显示遮罩层 
function popDivShow(popDivId, dragDivId, isShowMask) { 
if (isShowMask) { 
creatMask(popDivId); 
} 
var oWins = document.getElementById(popDivId); 
var oWins_title = document.getElementById(dragDivId); 
var bDrag = false; 
var disX = disY = 0; 
oWins.style.display = "block"; 
oWins_title.onmousedown = function(event) { 
var event = event || window.event; 
bDrag = true; 
disX = event.clientX - oWins.offsetLeft; 
disY = event.clientY - oWins.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 - oWins.offsetWidth; 
var maxT = document.documentElement.clientHeight - oWins.offsetHeight; 
iL = iL < 0 ? 0 : iL; 
iL = iL > maxL ? maxL : iL; 
iT = iT < 0 ? 0 : iT; 
iT = iT > maxT ? maxT : iT; 
oWins.style.marginTop = oWins.style.marginLeft = 0; 
oWins.style.left = iL + "px"; 
oWins.style.top = iT + "px"; 
return false; 
}; 
document.onmouseup = window.onblur = oWins_title.onlosecapture = function() { 
bDrag = false; 
oWins_title.releaseCapture && oWins_title.releaseCapture(); 
}; 
} 
// 隐藏弹出层 
function popDivHidden(popDivId) { 
var oWins = document.getElementById(popDivId); 
oWins.style.display = "none"; 
window.parent.document.body.removeChild(window.parent.document.getElementById("maskDiv")); 
} 
// 获取弹出层的zIndex 
function getZindex(popDivId) { 
var popDiv = document.getElementById(popDivId); 
var popDivZindex = popDiv.style.zIndex; 
return popDivZindex; 

} 
// 创建遮罩层 
function creatMask(popDivId) { 
// 参数w为弹出页面的宽度,参数h为弹出页面的高度,参数s为弹出页面的路径 
var maskDiv = window.parent.document.createElement("div"); 
maskDiv.id = "maskDiv"; 
maskDiv.style.position = "fixed"; 
maskDiv.style.top = "0"; 
maskDiv.style.left = "0"; 
maskDiv.style.zIndex = getZindex(popDivId) - 1; 
maskDiv.style.backgroundColor = "#333"; 
maskDiv.style.filter = "alpha(opacity=70)"; 
maskDiv.style.opacity = "0.7"; 
maskDiv.style.width = "100%"; 
maskDiv.style.height = (window.parent.document.body.scrollHeight + 50) + "px"; 
window.parent.document.body.appendChild(maskDiv); 
maskDiv.onmousedown = function() { 
window.parent.document.body.removeChild(window.parent.document.getElementById("maskDiv")); 
}; 
}