function drawBar(x,y,px,py,value,color){
    context.fillStyle = "#8e8c8c";
    context.fillRect(x,y,x+px,y+py);

    context.fillStyle = color;
    var percent = px*(value)/100.0;
    context.fillRect(x,y,x+percent,y+py);
}


drawBar(10,10,50,10,50,"#FF0");