> This would be true if these systems weren't constantly changing, both because the language keeps evolving and the runtime techniques keep evolving. Seconded

> This would be true if these systems weren't constantly changing, both because the language keeps evolving and the runtime techniques keep evolving. Seconded as a former SpiderMonkey engineer. As a safety guy, trusting an optimizing JIT is the stuff of my (professional) nightmares and the fact that the language keeps evolving, has semantics that very few people on Earth actually understand fully and that (very smart) developers keep cramming new optimizations within them. Oh, and add to that the fact that they're pretty much all written in C++, which is already the stuff of nightmares for safety professionals, and that they rely on garbage-collectors that need to walk both JavaScript and C++ heaps. I would trust a small, certified, non-optimizing implementation of a JS runtime much more than any of the juggernauts out there.