Get element by ID on the fly

I have lots of image on the page.
<img src="images/qview.gif" id="demo1" width="24" height="24" data-url="demo-modal.html" class="zoom-btn">
<img src="images/qview.gif" id="demo2" width="24" height="24" data-url="demo-modal.html" class="zoom-btn">… and so on
I want […]

See original post by invalid@example.com (yourwish)