调用jQuery滑出效果时闪烁的解决方法

var b1 = new slide_fix($('#Div3'));
$('#Button5').click(function(){b1.close();});//收
$('#Button6').click(function(){b1.open();});//開

function slide_fix(b){

var h = b.height();
var step = 600;
var time = 13;

this.open = function(){
timeRate(step,function(c,r){
var h1 = h*r;
b.height(h1);
if(c==1){b.show();}
});
}

this.close = function(){
timeRate(step,function(c,r){
var h1 = h *(1-r);
b.height(h1);
if(r==1){b.hide();}
});
}

function timeRate(step,fn){
var t = now();
var count = 1;
var timeId = setInterval(function(){
var t1 = now();
var rate = ((t1-t)>step) ? 1 : (t1-t)/step;
fn(count,rate);
if(rate==1){clearInterval(timeId);}
count++;
},time);
}

function now() {
return (new Date).getTime();
}
}