I've found the best way of equalizing heights/widths is just using display:table/table-row/table-cell. It handles resizing (responsiveness) and doesn't require any JavaScript.
But if in need to do this kind of things with Javascript, please take a look at https://github.com/atirip/jquery.pp This repo is not solely of dimensions, but you will find many useful and normalized (all your tags may even be mixed of content-box and border-box) dimension methods inside, both to measure and to set dimensions.
Then tables are obviously the way to go.
Resorting to JavaScript hacks when HTML/CSS provides you with a solution, despite it being "non-semantic" in some people's eyes, seems unnecessary. (Of course, there are cases where tables won't work either, and JS is your only option.)