Can I use JavaScript to check (irrespective of scrollbars) if an HTML element has overflowed its content? For example, a long div with small, fixed size, the overflow proper
I don't think this answer is perfect. Sometimes the scrollWidth/clientWidth/offsetWidth are the same even though the text is overflow.
This works well in Chrome, but not in IE and Firefox.
At last, I tried this answer: HTML text-overflow ellipsis detection
It's perfect and works well anywhere. So I choose this, maybe you can try, you won't disappoint.