js pops up the div and displays the mask layer_javascript skills

//------------- -------Pop-up layer-------------------
//popDivId: ID of pop-up layer div
//dragDivId: used for dragging ID of the animated div
//isShowMask: whether to display the mask layer
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();
};
}
//Hide the popup layer
function popDivHidden(popDivId) {
var oWins = document.getElementById(popDivId);
oWins.style.display = "none";
window.parent.document.body.removeChild(window. parent.document.getElementById("maskDiv"));
}
// Get the zIndex of the popup layer
function getZindex(popDivId) {
var popDiv = document.getElementById(popDivId);
var popDivZindex = popDiv.style.zIndex;
return popDivZindex;

}
// Create a mask layer
function creatMask(popDivId) {
// Parameter w is popup The width of the page, the parameter h is the height of the pop-up page, and the parameter s is the path of the pop-up page
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"));
};
}