Jquery作者John Resig自己封装的常用函数

//获取元素的样式值。
function getStyle(elem,name){
    if(elem.style[name]){
        return elem.style[name];
        }else if(elem.currentStyle){
            return elem.currentStyle[name];
            }else if(document.defaultView&&document.defaultView.getComputedStyle){
                name=name.replace(/([A-Z])/g,”-$1″);
                name=name.toLowerCase();
                var s=document.defaultView.getComputedStyle(elem,”");
                return s&&s.getPropertyValue(name);
                }else{
                    return null
                    }
    }
//获取元素相对于这个页面的x和y坐标。    
function pageX(elem){
    return elem.offsetParent?(elem.offsetLeft+pageX(elem.offsetParent)):elem.offsetLeft;
        }
function pageY(elem){
    return elem.offsetParent?(elem.offsetTop+pageY(elem.offsetParent)):elem.offsetTop;
        }
//获取元素相对于父元素的x和y坐标。        
function parentX(elem){
    return elem.parentNode==elem.offsetParent?elem.offsetLeft:pageX(elem)-pageX(elem.parentNode);
    }
function parentY(elem){
    return elem.parentNode==elem.offsetParent?elem.offsetTop:pageY(elem)-pageY(elem.parentNode);
    }
//获取使用css定位的元素的x和y坐标。
function posX(elem){
    return parseInt(getStyle(elem,”left”));
    }    
function posY(elem){
    return parseInt(getStyle(elem,”top”));
    }
//设置元素位置。    
function setX(elem,pos){
    elem.style.left=pos+”px”;
    }    
function setY(elem,pos){
    elem.style.top=pos+”px”;
    }
//增加元素X和y坐标。    
function addX(elem,pos){
    set(elem,(posX(elem)+pos));
    }
function addY(elem,pos){
    set(elem,(posY(elem)+pos));
    }
//获取元素使用css控制大小的高度和宽度    
function getHeight(elem){
    return parseInt(getStyle(elem,”height”));
    }
function getWidth(elem){
    return parseInt(getStyle(elem,”width”));
    }
//获取元素可能，完整的高度和宽度
function getFullHeight(elem){
    if(getStyle(elem,”display”)!=”none”){
        return getHeight(elem)||elem.offsetHeight;
        }else{
        var old=resetCss(elem,{display:”block”,visibility:”hidden”,position:”absolute”});
        var h=elem.clientHeight||getHeight(elem);
        restoreCss(elem,old);
        return h;
        }
    }
function getFullWidth(elem){
    if(getStyle(elem,”display”)!=”none”){
        return getWidth(elem)||elem.offsetWidth;
        }else{
        var old=resetCss(elem,{display:”block”,visibility:”hidden”,position:”absolute”});
        var w=elem.clientWidth||getWidth(elem);
        restoreCss(elem,old);
        return w;
        }
    }
//设置css，并保存旧的css
function resetCss(elem,prop){
    var old={};
    for(var i in prop){
        old[i]=elem.style[i];
        elem.style[i]=prop[i];
        }
        return old;
    }
function restoreCss(elem,prop){
    for(var i in prop){
        elem.style[i]=prop[i];
        }
    }
//显示和隐藏
function show(elem){
    elem.style.display=elem.$oldDisplay||” “;
    }
function hide(elem){
var curDisplay=getStyle(elem,”display”);
if(curDisplay!=”none”){
         elem.$oldDisplay=curDisplay;
    elem.style.display=”none”;
       }
    }
//设置透明度    
function setOpacity(elem,num){
    if(elem.filters){
        elem.style.filter=”alpha(opacity=”+num+”)”;
        }else{
            elem.style.opacity=num/100;
            }
    }
//滑动    
function slideDown(elem){
    var h=getFullHeight(elem);
    elem.style.height=”0px”;
    show(elem);
    for(var i=0;i<=100;i+=5){
        new function(){
                  var pos=i;
                  setTimeout(function(){elem.style.height=(pos/100*h)+”px”;},(pos*10));
                  }
        }
    }
//渐变
function fadeIn(elem){    
         show(elem);
         setOpacity(elem,0);
    for(var i=0;i<=100;i+=5){
        new function(){
                  var pos=i;
                  setTimeout(function(){setOpacity(elem,pos);},(pos+1)*10);
                  }
        }
    }
//获取鼠标光标相对于整个页面的位置。    
function getX(e){
    e=e||window.event;
    return e.pageX||e.clientX+document.body.scrollLeft;
    }
function getY(e){
    e=e||window.event;
    return e.pageY||e.clientY+document.body.scrollTop;
    }
//获取鼠标光标相对于当前元素的位置。
function getElementX(e){
    return (e&&e.layerX)||window.event.offsetX;
    }
function getElementY(e){
    return (e&&e.layerY)||window.event.offsetY;
    }
//获取页面的高度和宽度
function getPageHeight(){
    var de=document.documentElement;
    return document.body.scrollHeight||(de&&de.scrollHeight);
    }
function getPageWidth(){
    var de=document.documentElement;
    return document.body.scrollWidth||(de&&de.scrollWidth);
    }
//获取滚动条的位置。
function scrollX(){
    var de=document.documentElement;
    return self.pageXOffset||(de&&de.scrollLeft)||document.body.scrollLeft;
    }
function scrollY(){
    var de=document.documentElement;
    return self.pageYOffset||(de&&de.scrollTop)||document.body.scrollTop;
    }
//获取视口的高度和宽度。    
function windowHeight() {
    var de = document.documentElement;
    return self.innerHeight||(de && de.offsetHeight)||document.body.offsetHeight;
}
function windowWidth() {
    var de = document.documentElement;
    return self.innerWidth||( de && de.offsetWidth )||document.body.offsetWidth;
}

文章出自Corrie's Eye，原文查看Jquery作者John Resig自己封装的常用函数。