tl;dr: We believe there is a safer and easier way of writing a Jit. Current State Today, all browsers’ Jits share a similar design. This design makes extending the language or improving its performance time-consuming and complex, especially while avoiding security issues. For instance, at the time of this writing, our Jit relies upon ~15000 lines of carefully crafted, hand-written assembly code (~
![HolyJit: A New Hope](https://cdn-ak-scissors.b.st-hatena.com/image/square/97f51babb424b865cf32a087abd5e44b76964eb5/height=288;version=1;width=512/https%3A%2F%2Fblog.mozilla.org%2Fjavascript%2Fwp-content%2Fthemes%2FOneMozilla%2Fimg%2Fmozilla-wordmark.png)