Large websites and webapplications commonly provide pages that require loading of Megabytes (sometimes tens of Megabytes) of JavaScript code. That's bad both for the network and for the loading speed of the page. While source code minifiers can help, they make the code harder to read and debug, and sometimes slower to load. The JavaScript Binary AST is an ongoing work to extend the JavaScript Virtual Machines with a novel compression format that should make the code both smaller and faster to parse, without making it hard to read and debug.

We'll present the JavaScript Binary AST, as well as the tradeoffs we need to make between parsing speed and file size to guarantee safety and make it compatible with future versions of JavaScript.