取得 CSS background HEX值

// 取得 BackgroundColor to Hex

(function($){
	$.cssHooks.backgroundColor = {
	    get: function(elem) {
	        if (elem.currentStyle)
	            var bg = elem.currentStyle['background-color'];
	        else if (window.getComputedStyle)
	            var bg = document.defaultView.getComputedStyle(elem,
	                null).getPropertyValue('background-color');
	        if (bg.search('rgb') == -1)
	            return bg;
	        else {
	            bg = bg.match(/^rgb\((\d+),\s*(\d+),\s*(\d+)\)$/);
	            function hex(x) {
	                return ('0' + parseInt(x).toString(16)).slice(-2);
	            }
	            return '#' + hex(bg[1]) + hex(bg[2]) + hex(bg[3]);
	        }
	    }
	}
}(jQuery));