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jQuery Preload CSS Images
jQuery.preloadCssImages = function(){
var allImgs = [];//new array for all the image urls
var k = 0; //iterator for adding images
var sheets = document.styleSheets;//array of stylesheets
for(var i = 0; i<sheets .length; i++){//loop through each stylesheet
var cssPile = '';//create large string of all css rules in sheet
var csshref = (sheets[i].href) ? sheets[i].href : 'window.location.href';
var baseURLarr = csshref.split('/');//split href at / to make array
baseURLarr.pop();//remove file path from baseURL array
var baseURL = baseURLarr.join('/');//create base url for the images in this sheet (css file's dir)
if(baseURL!="") baseURL+='/'; //tack on a / if needed
if(document.styleSheets[i].cssRules){//w3
var thisSheetRules = document.styleSheets[i].cssRules; //w3
for(var j = 0; j<thisSheetRules.length; j++){
cssPile+= thisSheetRules[j].cssText;
}
}
else {
cssPile+= document.styleSheets[i].cssText;
}
//parse cssPile for image urls and load them into the DOM
var imgUrls = cssPile.match(/[^(]+.(gif|jpg|jpeg|png)/g);//reg ex to get a string of between a "(" and a ".filename"
if(imgUrls != null && imgUrls.length>0 && imgUrls != ''){//loop array
var arr = jQuery.makeArray(imgUrls);//create array from regex obj
jQuery(arr).each(function(){
allImgs[k] = new Image(); //new img obj
allImgs[k].src = (this[0] == '/' || this.match('http://')) ? this : baseURL + this; //set src either absolute or rel to css dir
k++;
});
}
}//loop
return allImgs;
};
//USAGE
//preload only
$.preloadCssImages();
//load into array
var preloadedImgs = $.preloadCssImages();
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