Popup Style DIV using Javascript

Update at November 10, 2010:

I am appalled by the numbers of visits this link is getting. Go through it just to understand how its basically done. But I suggest you dont use this code at all :)

Instead, use Malsup's Wonderful jQuery BlockUI Plugin : Demos are here


This sample is to create a pop-up using a DIV in the same page as passing values to and from the pop-up is easier

The Demo Pics are

Before Click



After Click



The CSS.

.opaqueLayer
{
display:none;
position:absolute;
top:0px;
left:0px;
opacity:0.6;
filter:alpha(opacity=60);
background-color: #000000;
z-Index:1000;
}

.questionLayer
{
position:absolute;
top:0px;
left:0px;
width:350px;
height:200px;
display:none;
z-Index:1001;
border:2px solid black;
background-color:#FFFFFF;
text-align:center;
vertical-align:middle;
padding:10px;
}

The Javascript.

function getBrowserHeight() {
var intH = 0;
var intW = 0;

if(typeof window.innerWidth == 'number' ) {
intH = window.innerHeight;
intW = window.innerWidth;
}
else if(document.documentElement && (document.documentElement.clientWidth || document.documentElement.clientHeight)) {
intH = document.documentElement.clientHeight;
intW = document.documentElement.clientWidth;
}
else if(document.body && (document.body.clientWidth || document.body.clientHeight)) {
intH = document.body.clientHeight;
intW = document.body.clientWidth;
}
return { width: parseInt(intW), height: parseInt(intH) };
}

function setLayerPosition() {
var shadow = document.getElementById('shadow');
var question = document.getElementById('question');

var bws = getBrowserHeight();
shadow.style.width = bws.width + 'px';
shadow.style.height = bws.height + 'px';
question.style.left = parseInt((bws.width - 350) / 2)+ 'px';
question.style.top = parseInt((bws.height - 200) / 2)+ 'px';
shadow = null;
question = null;
}

function showLayer() {
setLayerPosition();

var shadow = document.getElementById('shadow');
var question = document.getElementById('question');

shadow.style.display = 'block';
question.style.display = 'block';

shadow = null;
question = null;
}

function hideLayer() {
var shadow = document.getElementById('shadow');
var question = document.getElementById('question');

shadow.style.display = 'none';
question.style.display = 'none';

shadow = null;
question = null;
}

window.onresize = setLayerPosition;

And now, the HTML itself

<div id="shadow" class="opaqueLayer"> </div>
<div id="question" class="questionLayer">
<br />
<br />
<br />
This is the Popup DIV
<br />
Put anything here, Textbox or Buttons 
<br />
<br />
<br />
<input type="button" onclick="hideLayer();" value="Close" />
</div>
<table style="margin-left:auto;margin-right:auto;">
<tr>
<td style="height:120px;">

</td>
</tr>
<tr>
<td>
<button onclick="showLayer();">Click Me to see the Popup DIV</button>
</td>
</tr>
</table>

Explanation

Here two other DIVS are placed in the page which are hidden at first.
When clicking on the Button they are rendered visible.
These two DIVs are having different Z-Indexes that makes them look like a Popup Window.

Happy Coding!
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