jsOverlay - A function to overlay a webpage

jsoverlay.css

#jsOverlay
{
    background-color: #ffffff;
    opacity: 0.7;
    filter: alpha(opacity=70);
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 10;
}

jsoverlay.js

/**
 * Function to overlay a webpage
 * 
 * A Simple overlay function to block page access (modal page overlay)
 * 
 * Usage:
 * jsOverlay(true); // overlay's page
 * jsOverlay(false); // hides the overlay
 * 
 * @author Frank Neff <fneff89@gmail.com>
 * @licence LGPL v3 http://www.opensource.org/licenses/LGPL-3.0
 * @since 2011/11/22
 */
function jsOverlay( action ) {
    var overlaySelector = document.getElementById( "jsOverlay" ),
        overlayDiv = false;
            
    if( action === false ) {
        overlaySelector.style.display = "none";
    } else {
        if( overlaySelector === null ) {
            overlayDiv = document.createElement( "div" ) ;
            overlayDiv.id = "jsOverlay";
            document.getElementsByTagName( "body" )[0].appendChild( overlayDiv );
        } else {
            overlaySelector.style.display = "block";
        } 
    }
}