What would make offsetParent null?
I have made a test of 2,304 divs with unique combinations of values for position, display, and visibility, nested inside unique combinations of each of those values, and determined that:
an otherwise-valid element
that is a descendant of <body>
will not have an offsetParent value if:
- The element has
position:fixed(Webkit and IE9) - The element has
display:none(Webkit and FF) - Any ancestor has
display:none(Webkit and FF)
It is also reasonable to expect that an element that has no parent, or that is not added to the page itself (is not a descendant of the <body> of the page), will also have offsetParent==null.
If the document hasn't finished loading then offsetParent can be null