Comment by gergesim

I'd really avoid encouraging people to build up strings of html that you simply append to the DOM. This is a great way to run into XSS issues. Although the live DOM is slow,using a DocumentFragment (even if it's completely abstracted away with jQuery) is the right way to make modifications in bulk. The AJAX example is pretty convoluted so I'm not sure what you're proving, but building onto the promise chain seems like a better and much more readable code. Regarding ID selectors, querySelectorAll really minimizes the huge performance gain of id selectors only, and that's exactly what's used on any modern browser when you do a $(".foo")