emToPx - convert global em-based values to pixels

emToPx.js

/*
	* emToPx: convert a global em-based value to pixels
	* Copyright 2011, Scott Jehl, scottjehl.com
	* MIT License
	* Usage: emToPx function accepts a single number/float argument, returns a number
*/
var emToPx = (function( win ){
	var	doc		= win.document,
		body		= doc.body,
		prop		= "fontSize",
		dSize		= 16,
		valCache	= {},
		fBody;
		
	return function( val ){
		if( !valCache[ val ] ){
		
			//no body yet?
			if( !body ){
				fBody = doc.createElement( "body" );
				var docElem = doc.documentElement;
				docElem.insertBefore( fBody, docElem.firstElementChild || docElem.firstChild );
				body = fBody;
			}	
			
			//get body's font size
			if( body.currentStyle ){
				dSize = body.currentStyle.fontSize;
			}
			else if( window.getComputedStyle ){
				window.getComputedStyle( body,null ).getPropertyValue( "height" );
			}
			
			//cache val for repeat lookups
			valCache[ val ] = Math.round( val * dSize );
		}
		return valCache[ val ];
	};	
}( this ));

window.getComputedStyle( body,null ).getPropertyValue( "height" )

to

getComputedStyle( body,null ).height

otherwise... 👍

Awesome.