<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>每天一个JavaScript实例-操作元素定位元素</title>
<style>
div#a{
500px;
}
div{
border:1px solid #000;
padding:10px;
}
#cursor{
position:absolute;
background-color:#ff0;
20px;
height:20px;
left:50px;
top:300px;
}
</style>
<script>
function positionObject(obj){
var rect = obj.getBoundingClientRect();
return [rect.left,rect.top];
}
window.onload = function(){
var tst = document.documentElement.getBoundingClientRect();
alert(tst.top);
var cont = 'A';
var cursor = document.getElementById("cursor");
while(cont){
cont = prompt("where do you want to move the cursor block?","A");
if(cont){
cont = cont.toLowerCase();
if(cont == "a"||cont=="b"||cont=="c"){
var elem = document.getElementById(cont);
var pos = positionObject(elem);
console.log(pos);
cursor.setAttribute("style","top:"+pos[1]+"px;"+"left:"+pos[0]+"px");
}
}
}
}
</script>
</head>
<body>
<div id = "a">
<p>A</p>
<div id ="b">
<p>B</p>
<div id="c">
<p>C</p>
</div>
</div>
</div>
<div id="cursor">
</div>
</body>
</html>