//get a style property (name) of a specific element (elem) function getStyle(elem, name) { 　　// if the property exists in style[], then it's been set 　　//recently (and is current) if(elem.style[name]) return elem.style[name]; //otherwise, try to use IE's method else if (elem.currentStyle) return elem.currentStyle[name]; //Or the W3C's method, if it exists else if (document.defaultView && document.defaultView.getComputedStyle) { 　　　　　　//it uses the traditional 'text-align' style of rule writing 　　　　　　//instead of textAlign name = name.replace(/[A-Z]/g, '-$1'); name = name.toLowerCase(); //get the style object and get the value of the property ( if it exists) 　　　　　　var s = document.defaultView.getComputedStyle(elem,''); return s && s.getPropertyValue(name); 　　} else return null; }

//find the x (horizontal, Left) position of an element function pageX(elem) { 　　//see if we're at the root element, or not return elem.offsetParent ? //if we can still go up, add the current offset and recurse upwards 　　　　　　elem.offsetLeft + pageX(elem.offsetParent) : 　　　　　　//otherwise, just get the current offset 　　　　　　elem.offsetLeft; } //find the y (vertical, top) position of an element function pageY(elem) { 　　//see if we're at the root element, or not 　　return elem.offsetParent ? //if we can still go up, add the current offset and recurse upwards 　　 elem.offsetTop + pageY(elem.offsetParent) : //otherwise, just get the current offset elem.offsetTop; }

//find the horizontal position of an element within its parent function parentX(elem) { 　　//if the offsetParent is the element's parent, break early 　　return elem.parentNode == elem.offsetParent ? elem.offsetLeft : // otherwise, we need to find the position relative to the entire // page for both elements, and find the difference pageX(elem) - pageX(elem.parentNode); } //find the vertical positioning of an element within its parent function parentY(elem) { 　　//if the offsetParent is the element's parent, break early return elem.parentNode == elem.offsetParent ? 　　　　elem.offsetTop : // otherwise, we need to find the position relative to the entire // page for both elements, and find the difference pageY(elem) - pageY(elem.parentNode); }

//find the left position of an element function posX(elem) { 　　//get the computed style and get the number out of the value return parseInt(getStyle(elem, 'left')); } //find the top position of an element function posY(elem) { 　　//get the computed style and get the number out of the value return parseInt(getStyle(elem, 'top')); }

//a function for setting the horizontal position of an element function setX(elem, pos) { 　　//set the 'left' css property, using pixel units 　　elem.style.left = pos + 'px'; } //a function for setting the vertical position of an element function setY(elem, pos) { 　　//set the 'top' css property, using pixel units 　　elem.style.top = pos + 'px'; }

//a function for adding a number of pixels to the horizontal //position of an element function addX(elem, pos) { 　　//get the current horz. position and add the offset to it setX(elem, posX(elem) + pos); } //a function that can be used to add a number of pixels to the //vertical position of an element function addY(elem, pos) { 　　//get the current vertical position and add the offset to it setY(elem, posY(elem) + pos); }

function getHeight(elem) { 　　return parseInt(getStyle(elem, 'height')); } function getWidth(elem) { 　　return parseInt(getStyle(elem, 'width')); }

//查找元素完整的、可能的高度 function fullHeight(elem) { 　　//如果元素是显示的，那么使用offsetHeight就能得到高度，如果没有offsetHeight，则使用getHeight() 　　if(getStyle(elem, 'display') != 'none') 　　　　　　return elem.offsetHeight || getHeight(elem); //否则，我们必须处理display为none的元素，所以重置它的css属性以获得更精确的读数 var old = resetCSS(elem, { 　　display:'', visibility:'hidden', position:'absolute' }); //使用clientHeigh找出元素的完整高度，如果还不生效，则使用getHeight函数 var h = elem.clientHeight || getHeight(elem); //最后，恢复其css的原有属性 restoreCSS(elem, old); //并返回元素的完整高度 return h; } //查找元素完整的、可能的宽度 function fullWidth(elem) { 　　//如果元素是显示的，那么使用offsetWidth就能得到宽度，如果没有offsetWidth,则使用getWidth() if(getStyle(elem, 'display') != 'none') 　　　　return elem.offsetWidth || getWidth(elem); //否则，我们必须处理display为none的元素，所以重置它的css以获取更精确的读数 var old = resetCSS(elem, { 　　　display:'', visibility:'hidden', position:'absolute' }); //使用clientWidth找出元素的完整高度，如果还不生效，则使用getWidth函数 var w = elem.clientWidth || getWidth(elem); //最后，恢复原有CSS 　restoreCSS(elem, old); //返回元素的完整宽度 return w; } //设置一组CSS属性的函数 function resetCSS(elem, prop) { 　　var old = {}; //遍历每个属性 for(var i in prop) { 　　//记录旧的属性值 old[i] = elem.style[i]; 　　　　//设置新的值 　　　　elem.style[i] = prop[i]; } return old; } //恢复原有CSS属性 function restoreCSS(elem, prop) { 　　for(var i in prop) 　　　　elem.style[i] = prop[i]; }