Preload background-images from media query CSS files

gistfile1.txt

function preload(arrayOfImages) {
    $(arrayOfImages).each(function(){
       
        // Find 4 digit pixel reference in filename
        var digits = 4;
        var str = this;
        var regex = new RegExp("\\d{"+digits+"}", "g");
        var match = str.match(regex);
        
        // If bg image is smaller than user's screen width
        if ( match < screen.width ) {
	        (new Image()).src = this;
	}

    });
} 

function getBgImages(selector, cssFile) {

    var styles, imgs = [];

	// Find specified stylesheet
	$.each(document.styleSheets, function(i,sheet) {
		var reg = new RegExp(cssFile, 'g');
		var results = reg.test(sheet.href);
		if ( results ) {
			styles = sheet.rules || sheet.cssRules;
		}
	});
    
    // Loop through stylesheet and look for selector
    $.each(styles, function(i,item) {
    
    	// If style href equals css file argument
    	if ( item.parentStyleSheet['href'] == cssFile ) {
    		// Loop through rules
    		$.each(item.parentStyleSheet.cssRules, function(i,v) {
    			if ( v.selectorText == selector ) {
    				var css = v.cssText;
    				var bg = css.match(/url\([^)]+\)/g);
    				$.each(bg, function(i,v) {
    					var img = v.replace('url(', '');
    					img = img.replace(')', '');
    					imgs.push(img);
    				});
    			}
    		});
    	}
    });
    
    return imgs;   
}

// Preloader
$(window).load(function() {

	var cssFiles = $('link[media]'), files = {};

	$.each(cssFiles, function(i,item) {
		
	    // Find 4 digit pixel reference in filename
	    var digits = 4;
	    var str = item.href;
	    var regex = new RegExp("\\d{"+digits+"}", "g");
	    var match = str.match(regex);
		
		if ( match == null )
			match = 0;
		
		if ( item.media != 'all' )
			files[match] = item.href;
			
	});

	var bodyClass = '.'+$('body').attr('class');
	
	// Preload background images referenced by body class	
	$.each(files, function(k,v) {
		if ( screen.width > k )
			preload(getBgImages(bodyClass+' div#background', v));
	});
	
});