 
$("#result").text(isOverlap("one","two")+","+isOverlap("one","three")+","+isOverlap("two","three")); 
function isOverlap(idOne,idTwo){ 
var objOne=$("#"+idOne), 
objTwo=$("#"+idTwo), 
offsetOne = objOne.offset(), 
offsetTwo = objTwo.offset(), 
topOne=offsetOne.top, 
topTwo=offsetTwo.top, 
leftOne=offsetOne.left, 
leftTwo=offsetTwo.left, 
widthOne = objOne.width(), 
widthTwo = objTwo.width(), 
heightOne = objOne.height(), 
heightTwo = objTwo.height(); 
var leftTop = leftTwo > leftOne && leftTwo < leftOne+widthOne 
&& topTwo > topOne && topTwo < topOne+heightOne, 
rightTop = leftTwo+widthTwo > leftOne && leftTwo+widthTwo < leftOne+widthOne 
&& topTwo > topOne && topTwo < topOne+heightOne, 
leftBottom = leftTwo > leftOne && leftTwo < leftOne+widthOne 
&& topTwo+heightTwo > topOne && topTwo+heightTwo < topOne+heightOne, 
rightBottom = leftTwo+widthTwo > leftOne && leftTwo+widthTwo < leftOne+widthOne 
&& topTwo+heightTwo > topOne && topTwo+heightTwo < topOne+heightOne; 
return leftTop || rightTop || leftBottom || rightBottom; 
} 

原理很簡單，就是判斷一個元素的四個點(diǎn)是否在另一個元素內(nèi)部。
完整演示代碼：

復(fù)制代碼代碼如下:

 
JSCode 
LoginResult JavaScript HTML CSS ALL Edit Share 
$("#result").text(isOverlap("one","two")+","+isOverlap("one","three")+","+isOverlap("two","three")); 
function isOverlap(idOne,idTwo){ 
var objOne=$("#"+idOne), 
objTwo=$("#"+idTwo), 
offsetOne = objOne.offset(), 
offsetTwo = objTwo.offset(), 
topOne=offsetOne.top, 
topTwo=offsetTwo.top, 
leftOne=offsetOne.left, 
leftTwo=offsetTwo.left, 
widthOne = objOne.width(), 
widthTwo = objTwo.width(), 
heightOne = objOne.height(), 
heightTwo = objTwo.height(); 
var leftTop = leftTwo > leftOne && leftTwo < leftOne+widthOne 
&& topTwo > topOne && topTwo < topOne+heightOne, 
rightTop = leftTwo+widthTwo > leftOne && leftTwo+widthTwo < leftOne+widthOne 
&& topTwo > topOne && topTwo < topOne+heightOne, 
leftBottom = leftTwo > leftOne && leftTwo < leftOne+widthOne 
&& topTwo+heightTwo > topOne && topTwo+heightTwo < topOne+heightOne, 
rightBottom = leftTwo+widthTwo > leftOne && leftTwo+widthTwo < leftOne+widthOne 
&& topTwo+heightTwo > topOne && topTwo+heightTwo < topOne+heightOne; 
return leftTop || rightTop || leftBottom || rightBottom; 
} 
<div id="one">One</div> 
<div id="two">Two</div> 
<div id="three">Three</div> 
<h1 id="result"></h1> 
div{ 
width:200px; 
height:200px; 
background:#EEE; 
} 
#two{ 
position:absolute; 
left:100px; 
top:50px; 
background:#F60; 
} 
DownLoad 
<!DOCTYPE html> 
<html> 
<head> 
<meta charset="utf-8"/> 
<title>JSCode demo</title> 
<style type="text/css"> 
div{ 
width:200px; 
height:200px; 
background:#EEE; 
} 
#two{ 
position:absolute; 
left:100px; 
top:50px; 
background:#F60; 
} 
</style> 
<script src="/js_lib/jQuery-1.7.2.js" type="text/javascript"></script> 
</head> 
<body> 
<div id="one">One</div> 
<div id="two">Two</div> 
<div id="three">Three</div> 
<h1 id="result"></h1> 
<script type="text/javascript"> 
$("#result").text(isOverlap("one","two")+","+isOverlap("one","three")+","+isOverlap("two","three")); 
function isOverlap(idOne,idTwo){ 
var objOne=$("#"+idOne), 
objTwo=$("#"+idTwo), 
offsetOne = objOne.offset(), 
offsetTwo = objTwo.offset(), 
topOne=offsetOne.top, 
topTwo=offsetTwo.top, 
leftOne=offsetOne.left, 
leftTwo=offsetTwo.left, 
widthOne = objOne.width(), 
widthTwo = objTwo.width(), 
heightOne = objOne.height(), 
heightTwo = objTwo.height(); 
var leftTop = leftTwo > leftOne && leftTwo < leftOne+widthOne 
&& topTwo > topOne && topTwo < topOne+heightOne, 
rightTop = leftTwo+widthTwo > leftOne && leftTwo+widthTwo < leftOne+widthOne 
&& topTwo > topOne && topTwo < topOne+heightOne, 
leftBottom = leftTwo > leftOne && leftTwo < leftOne+widthOne 
&& topTwo+heightTwo > topOne && topTwo+heightTwo < topOne+heightOne, 
rightBottom = leftTwo+widthTwo > leftOne && leftTwo+widthTwo < leftOne+widthOne 
&& topTwo+heightTwo > topOne && topTwo+heightTwo < topOne+heightOne; 
return leftTop || rightTop || leftBottom || rightBottom; 
} 
</script> 
</body> 
</html> 
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