How to get the coordinates of the end of selected text with javascript?

My problem is similar to this, b开发者_StackOverflowut I need a way to get the coordinates of the right side of the selection with Javascript in Firefox. I made a small example to show what I mean:

The code I got from the other post is the following:

var range = window.getSelection().getRangeAt(0);
var dummy = document.createElement("span");
range.insertNode(dummy);
var box = document.getBoxObjectFor(dummy);
var x = box.x, y = box.y;
dummy.parentNode.removeChild(dummy);

This gives me the coordinates of the beginning of the selection. Is there any way to retrieve the coordinates of the end of the selection?

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Yes. That bit's quite simple: you just need to call collapse(false) on the Range obtained from the selection. Be aware that document.getBoxObjectFor() has now been removed from Mozilla, so you need the dummy element's getBoundingClientRect() method instead:

var range = window.getSelection().getRangeAt(0);
range.collapse(false);
var dummy = document.createElement("span");
range.insertNode(dummy);
var rect = dummy.getBoundingClientRect();
var x = rect.left, y = rect.top;
dummy.parentNode.removeChild(dummy);

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var r = range.cloneRange();
r.collapse(false); // collapses range clone to end of original range
r.insertNode(dummy);
// document.getBoxObjectFor(dummy), etc.