javascript取元件位置

<SCRIPT language=JavaScript type=text/javascript>
<!--

function getElementPos(elementId) {

 var ua = navigator.userAgent.toLowerCase();
 var isOpera = (ua.indexOf('opera') != -1);
 var isIE = (ua.indexOf('msie') != -1 && !isOpera); // not opera spoof

 var el = document.getElementById(elementId);

 if(el.parentNode === null || el.style.display == 'none')
 {
  return false;
 }

 var parent = null;
 var pos = [];
 var box;

 if(el.getBoundingClientRect) //IE
 {
  box = el.getBoundingClientRect();
  var scrollTop = Math.max(document.documentElement.scrollTop, document.body.scrollTop);
  var scrollLeft = Math.max(document.documentElement.scrollLeft, document.body.scrollLeft);

  return {x:box.left + scrollLeft, y:box.top + scrollTop};
 }
 else if(document.getBoxObjectFor) // gecko
 {
  box = document.getBoxObjectFor(el);
    
  var borderLeft = (el.style.borderLeftWidth)?parseInt(el.style.borderLeftWidth):0;
  var borderTop = (el.style.borderTopWidth)?parseInt(el.style.borderTopWidth):0;

  pos = [box.x - borderLeft, box.y - borderTop];
 }
 else // safari & opera
 {
  pos = [el.offsetLeft, el.offsetTop];
  parent = el.offsetParent;
  if (parent != el) {
   while (parent) {
    pos[0] += parent.offsetLeft;
    pos[1] += parent.offsetTop;
    parent = parent.offsetParent;
   }
  }
  if (ua.indexOf('opera') != -1
   || ( ua.indexOf('safari') != -1 && el.style.position == 'absolute' ))
  {
    pos[0] -= document.body.offsetLeft;
    pos[1] -= document.body.offsetTop;
  }
 }
  
 if (el.parentNode) { parent = el.parentNode; }
 else { parent = null; }
 
 while (parent && parent.tagName != 'BODY' && parent.tagName != 'HTML')
 { // account for any scrolled ancestors
  pos[0] -= parent.scrollLeft;
  pos[1] -= parent.scrollTop;
 
  if (parent.parentNode) { parent = parent.parentNode; }
  else { parent = null; }
 }
 return {x:pos[0], y:pos[1]};
}

function setPosition()
{
 var pos = getElementPos('test_1');

 var temp = document.getElementById("test_2");
 temp.style.position = "absolute";
 temp.style.top = pos.y + "px";
 temp.style.left = pos.x + "px";
}

//-->
</SCRIPT>

 

<DIV id=test_1

style="BORDER-RIGHT: blue 1px solid; BORDER-TOP: blue 1px solid; FLOAT: left; BORDER-LEFT: blue 1px solid; WIDTH: 200px; MARGIN-RIGHT: 100px; BORDER-BOTTOM: blue 1px solid; HEIGHT: 200px"></DIV>

<DIV id=test_2

style="BACKGROUND: red; OVERFLOW: hidden; WIDTH: 10px; HEIGHT: 10px"></DIV><BR

class=clear><BR><INPUT onclick=setPosition() type=button value="點此移動紅色元素到有藍色邊框 DIV 的左上方">

<BR><BR><!--************************************* 執行個體代碼結束 *************************************--></DIV>

 

 

 

</BODY></HTML>