jquery.cssCapture.js

(function($) {

  var head = $('head');

  $.cssCapture = function(selectors, manipulate) {

    var stylesheets = document.styleSheets,
        selectors = selectors.split(/\s*,\s*/),m
        promises = [],
        matched = [],
        newStyles = [];

    $.each(stylesheets, function() {
      var rules = this.cssRules;
      if ( ! rules ) return;
      $.each(rules, function() {
        for ( var i = 0, l = selectors.length; i < l; ++i ) {
          var regex = new RegExp('^\\' + selectors[i] + '$');
          if ( this.type === 1 ) {
            var ruleSelectors = this.selectorText.split(/\s*,\s*/),
                matches = false;
            for ( var j = 0, m = ruleSelectors.length; j < m; ++j ) {
              if ( ruleSelectors[i].match(regex) ) {
                matches = true;
                break;
              }
            }
            if ( matches && this.style.backgroundImage.match(/url\(/) ) {
              matched.push(this.selectorText);
              promises.push($.capture(this.style.backgroundImage.replace(/.*?url\(['"]?(.*?)['"]?\)/, "$1")));
            }
          }
        }
      });
    });

    var deferred = $.when.apply($, promises);
    deferred.then(function() {
      function done() {
        var stylesheet = stylesheets[stylesheets.length - 1];
        $.each(arguments, function(i) {
          stylesheet.insertRule(matched[i] + '{background-image:url(' + ( this.src ? this.src : this ) + ')}', stylesheet.cssRules.length);
        });
      }
      if ( manipulate && $.isFunction(manipulate) ) {
        return manipulate.apply(done, arguments);
      }
      done.apply(null, arguments);
    });
    return deferred.promise();

  };

})(jQuery);