Progressbar with BG-hack

gistfile1.js

(function($){
// bgImgPos hack
    if(!document.defaultView || !document.defaultView.getComputedStyle){ // IE6-IE8
        var oldCurCSS = $.curCSS;
        $.curCSS = function(elem, name, force){
            if(name === 'background-position'){
                name = 'backgroundPosition';
            }
            if(name !== 'backgroundPosition' || !elem.currentStyle || elem.currentStyle[ name ]){
                return oldCurCSS.apply(this, arguments);
            }
            var style = elem.style;
            if ( !force && style && style[ name ] ){
                return style[ name ];
            }
            return oldCurCSS(elem, 'backgroundPositionX', force) +' '+ oldCurCSS(elem, 'backgroundPositionY', force);
        };
    }
 
    var oldAnim = $.fn.animate;
    $.fn.animate = function(prop){
        if('background-position' in prop){
            prop.backgroundPosition = prop['background-position'];
            delete prop['background-position'];
        }
        if('backgroundPosition' in prop){
            prop.backgroundPosition = '('+ prop.backgroundPosition;
        }
        return oldAnim.apply(this, arguments);
    };
 
    function toArray(strg){
        strg = strg.replace(/left|top/g,'0px');
        strg = strg.replace(/right|bottom/g,'100%');
        strg = strg.replace(/([0-9\.]+)(\s|\)|$)/g,"$1px$2");
        var res = strg.match(/(-?[0-9\.]+)(px|\%|em|pt)\s(-?[0-9\.]+)(px|\%|em|pt)/);
        return [parseFloat(res[1],10),res[2],parseFloat(res[3],10),res[4]];
    }
 
    $.fx.step. backgroundPosition = function(fx) {
        if (!fx.bgPosReady) {
            var start = $.curCSS(fx.elem,'backgroundPosition');
            if(!start){//FF2 no inline-style fallback
                start = '0px 0px';
            }
 
            start = toArray(start);
            fx.start = [start[0],start[2]];
            var end = toArray(fx.end);
            fx.end = [end[0],end[2]];
 
            fx.unit = [end[1],end[3]];
            fx.bgPosReady = true;
        }
        //return;
        var nowPosX = [];
        nowPosX[0] = ((fx.end[0] - fx.start[0]) * fx.pos) + fx.start[0] + fx.unit[0];
        nowPosX[1] = ((fx.end[1] - fx.start[1]) * fx.pos) + fx.start[1] + fx.unit[1];
        fx.elem.style.backgroundPosition = nowPosX[0]+' '+nowPosX[1];
 
    };
    // end bgImgPos hack
 
    $.fn.progressBar= function(e){
        var eu = (e.imgurl == undefined) ? 'progressbar.png' : e.imgurl; // image url
        var ep = (e.progress == undefined) ? 0 : e.progress; // progress value
        var el = (e.label == undefined) ? true : e.label; // label display
        var et = (e.type == undefined) ? '%' : e.type; // progressbar type
        var iw = 400; // image width
        var lp =$(this).css('backgroundPosition'); // last position
        var cw = $(this).width(); // current width
        var go = cw*(ep/100); // value to go
        iw=(-1 * iw)+ 'px';     
 
        if(ep<=100){
            $(this)
            .css({'background-image' : 'url('+eu+')', backgroundPosition: lp})
            .animate({'background-position': (go+parseInt(iw))+'px 0px'},1000, function(){if(el==true)$('label', this).html(ep+et);})
            .animate({backgroundPosition: (go+parseInt(iw))+'px 0px'},1000);
        }
    };
})(jQuery); 

// @ we are using it 
$('#prog').progressBar({
    imgurl : 'progressblue.png',
    progress : 50,
    type : '%',
    label : true
});