I am wondering how I can get the number of pixels (or measurement in general) from a div to the top of the window in Javascript. I am not looking for an offset y in relation to the document, simply to the top of where the browser is displaying. I tried the "answered" solution here: Is it possible to get the position of div within the browser viewport? Not within the document. Within the window, but at least in Safari, I am running into a problem where it returns the same number no matter where the div's really are.
Thanks for any help!
The existing answers are now outdated. The getBoundingClientRect()
method has been around for quite a while now, and does exactly what this question asks for. Plus it is supported across all browsers.
From this MDN page:
The returned value is a TextRectangle object, which contains read-only left, top, right and bottom properties describing the border-box, in pixels, with the top-left relative to the top-left of the viewport.
You use it like so:
var viewportOffset = el.getBoundingClientRect();
// these are relative to the viewport
var top = viewportOffset.top;
var left = viewportOffset.left;
//First get the correct geometry for the browser
(function(){
Run= window.Run || {};
if(window.pageYOffset!= undefined){
Run.topLeftScroll= function(hoo){
var wo= [window.pageXOffset, window.pageYOffset]
if(hoo && hoo.nodeType== 1){
hoo= mr(hoo);
var T= 0, L= 0;
while(hoo){
L+= hoo.offsetLeft;
T+= hoo.offsetTop;
hoo= hoo.offsetParent;
}
wo= [L, T, wo[0], wo[1]];
}
return wo;
}
}
else if(document.body.scrollTop!== undefined){
Run.topLeftScroll= function(hoo){
var B= document.body;
var D= document.documentElement;
D= (D.clientHeight)? D: B;
wo= [D.scrollLeft, D.scrollTop];
if(hoo && hoo.nodeType== 1){
hoo= mr(hoo);
var T= 0, L= 0;
while(hoo){
L+= hoo.offsetLeft;
T+= hoo.offsetTop;
hoo= hoo.offsetParent;
}
wo= [L, T, wo[0], wo[1]];
}
return wo;
}
}
})()
// shortcut function
if(window.Run && Run.topLeftScroll){
Run.getPosition= function(who, wch){
var A= Run.topLeftScroll(who);
if(!wch) return A;
switch(wch.toUpperCase()){
case 'X': return A[0];// element Left in document
case 'Y': return A[1];// element Top in document
case 'L': return A[0]-A[2];// Left minus scroll
case 'T': return A[1]-A[3];// Top minus scroll
case 'SL': return A[2];// scroll Left
case 'ST': return A[3];// scroll Top
default: return 0;
}
// all returns are integers (pixels)
}
}
Check out what the JS Frameworks have to offer. Mostly, they have worked out all - or at least most - of the browser specific problems and specialties.
In Prototype, there are the scrollOffset() functions. I'm not familiar enough with JQuery to point you to the right manual page but here is a question that seems to go towards the right direction.
I've shearshed a little bit and found this :
function getOffsetPosition(el_id, side){
element = document.getElementById(el_id);
newNode = document.createElement("div");
newNode.innerHTML = "<div style=\"height: 12px;\"></div>";
element.insertBefore(newNode, element.firstChild);
iVal = 0;
oObj = element;
var sType = "oObj.offset"+side;
while (oObj && oObj.tagName != "html") {
iVal += eval(sType);
oObj = oObj.offsetParent;
}
element.removeChild(newNode);
return iVal;
}
If that can help you ^^
This answer tells you how to get the x and y coords of an element with respect the origin (top left) of a document. You just need to add the .scrollTop value to the y coord to get the distance in pixels from div to top of viewport.
来源:https://stackoverflow.com/questions/1960082/position-of-div-in-relation-to-the-top-of-the-viewport