This presentation demonstrates how learning just a little bit about JavaScript engine internals can help you improve the run-time performance of your JavaScript code — not just in V8 specifically, but across all JavaScript engines! I’ll start by explaining how V8 handles arrays behind the scenes, and especially how it can optimize operations on them. I can do all of this with my “JS developer” hat on, i.e. without showing a single line of C++. This knowledge leads to useful insights for JavaScript developers wishing to improve their code’s run-time performance. In the end, the audience will walk away with several practical performance tips, and a deeper understanding of what’s going on under the hood. Slides: https://slidr.io/mathiasbynens/v8-internals-for-javascript-developers#1 Writeup: https://v8project.blogspot.com.au/2017/09/elements-kinds-in-v8.html