用 Javascript 获取指定页面元素的位置

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]};

}