Hello there
I have an element with fixed position, I can't detect position and must be use javascript clearly, without frameworks (jquery, mootools, etc).
Use:
var boundingBox = node.getBoundingClientRect();
Check out the result, you have an object like this:
top : 0,
right : 0,
bottom : 0,
left : 0,
width : 0,
height : 0