用js模拟JQuery的show与hide动画函数代码

//根据ID返回dom元素 
var $ = function(id){return document.getElementById(id);} 
//返回dom元素的当前某css值 
var getCss = function(obj,name){ 
//ie 
if(obj.currentStyle) { 
return obj.currentStyle[name]; 
} 
//ff 
else { 
var style = document.defaultView.getComputedStyle(obj,null); 
return style[name]; 
} 
}

Hide函数：

var hide = function(obj,speed,fn){ 
obj = $(obj); if (!speed) { 
obj.style.display = 'none'; 
return; 
} 
else{ 
speed = speed==='fast'?20:speed==='normal'?30:50; 
obj.style.overflow = 'hidden'; 
} 
//获取dom的宽与高 
var oWidth = getCss(obj,'width'), oHeight = getCss(obj,'height'); 
//每次dom的递减数(等比例) 
var wcut = 10*(+oWidth.replace('px','') / +oHeight.replace('px','')),hcut = 10; 
//处理动画函数 
var process = function(width,height){ 
width = +width-wcut>0?+width-wcut:0; 
height = +height-hcut>0?+width-hcut:0; 
//判断是否减完了 
if(width !== 0 || height !== 0) { 
obj.style.width = width+'px'; 
obj.style.height = height+'px'; 
setTimeout(function(){process(width,height);},speed); 
} 
else { 
//减完后，设置属性为隐藏以及原本dom的宽与高 
obj.style.display = 'none'; 
obj.style.width = oWidth; 
obj.style.height = oHeight; 
if(fn)fn.call(obj); 
} 
} 
process(oWidth.replace('px',''),oHeight.replace('px','')); 
}

Show函数与Hide函数类似，只是思路相反而已

var show = function(obj,speed,fn){ obj = $(obj); 
if (!speed) { 
obj.style.display = 'block'; 
return; 
} 
else{ 
speed = speed==='fast'?20:speed==='normal'?30:50; 
obj.style.overflow = 'hidden'; 
} 
var oWidth = getCss(obj,'width').replace('px',''), oHeight = getCss(obj,'height').replace('px',''); 
var wadd = 10*(+oWidth / +oHeight),hadd = 10; 
obj.style.width = 0+'px'; 
obj.style.height = 0+'px'; 
obj.style.display = 'block'; 
var process = function(width,height){ 
width = +oWidth-width<wadd?+oWidth:wadd+width; 
height = +oHeight-height<hadd?oHeight:hadd+height; 
if(width !== +oWidth || height !== +oHeight) { 
obj.style.width = width+'px'; 
obj.style.height = height+'px'; 
setTimeout(function(){process(width,height);},speed); 
} 
else { 
obj.style.width = oWidth+'px'; 
obj.style.height = oHeight+'px'; 
if(fn)fn.call(obj); 
} 
} 
process(0,0); 
}

调用方式如：

hide('a','normal',function(){ 
show('a','normal'); 
});

呃。。。感觉写得好冗余，但不知要如何再优化，希望有高手能写个精简些的。。。