javascript 缓冲效果实现代码 推荐

function f_s() {
var obj = document.getElementById("top");
obj.style.display = "block";
obj.style.height = "1px";

var sw = function () {
var s_width = parseInt(obj.style.height);
if (s_width < 350) {
obj.style.height = (s_width + Math.ceil((350 - s_width) / 15)) + "px";
}
else {
clearInterval(st);
}
}
var st = window.setInterval(sw, 1);
}

/*
函数名称: Scroll
Scroll(obj, h, s)
参数说明:
obj,[object] id值或对象. 必需
h,[height] 展开后的高度. 可选(默认为200px)
s,[speed] 展开速度,值越小展开速度越慢. 可选(默认为1.2){建议取值为1.1到2.0之间[例如:1.17]}.
函数返回值:
true 展开(对象的高度等于展开后的高度)
false 关闭(对象的高度等于原始高度)
*/
function Scroll(obj, h, s){
if(obj == undefined){return false;}
var h = h || 200;
var s = s || 1.2;
var obj = typeof(obj)=="string"?document.getElementById(obj):obj;
var status = obj.getAttribute("status")==null;
var oh = parseInt(obj.offsetHeight);
obj.style.height = oh;
obj.style.display = "block";
obj.style.overflow = "hidden";
if(obj.getAttribute("oldHeight") == null){
obj.setAttribute("oldHeight", oh);
}else{
var oldH = Math.ceil(obj.getAttribute("oldHeight"));
}
var reSet = function(){
if(status){
if(oh < h){
oh = Math.ceil(h-(h-oh)/s);
obj.style.height = oh+"px";
}else{
obj.setAttribute("status",false);
window.clearInterval(IntervalId);
}
}else{
obj.style.height = oldH+"px";
obj.removeAttribute("status");
window.clearInterval(IntervalId);
}
}
var IntervalId = window.setInterval(reSet,10);
return status;
}