获取元素相的坐标
所有现代浏览器均支持以下3个属性:offsetParent,offsetLeft,offsetTop
不同点在于有的浏览器的offsetParent是直接指向根节点的，有的不是

function pageX(elem){        //查看是否位于根元素return elem.offsetParent?elem.offsetLeft + pageX(elem.offsetParent):elem.offsetLeft;}function pageY(elem){return elem.offsetParent?elem.offsetTop + pageY(elem.offsetParent):elem.offsetTop;}

获取相对于父元素的位置

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);}

获取相对于CSS容器的位置

function cssX(elem){return parseInt(getStyle(elem,"left"));}function cssY(elem){return parseInt(getStyle(elem,"top"));}

获取隐藏元素的高度

//获取隐藏元素的高度和宽度function fullHeight(elem) {if(getStyle(elem,"display") != "none") {return elem.offsetHeight || getHeight(elem);}var old = resetCss(elem, {display:"",visibility:"hidden",position:"absolute"});var h = elem.offsetHeight || getHeight(elem);restoreCss(elem,old);return h;}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,old) {for(var i in prop) {elem.style[i] = old[i];}}