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| function scrollTopBy(endTop,easing){
var beginTop = $(window).scrollTop();
var range = endTop - beginTop;
var start = 0;
var step = 20;
var total = Math.abs(Math.ceil(range / step));
var timer = null;
function startScroll(){
if(start <= total){
var top = Math.round(easing(start,beginTop,range,total));
window.scrollTo(0,top);
start ++;
timer = setTimeout(function(){
startScroll();
},13);
}else{
clearTimeout(timer);
timer = null;
}
}
startScroll();
}
var endTop = $(window).scrollTop();
scrollTopBy(endTop,function(t, b, c, d) {
return c*t/d + b;
});
|
