The Javascript JIT arms race was the most heavily funded dynamic language arms race since forever - involving three major players (Apple, Google, Mozilla), dedicated teams, tons of benchmarks, constant tracking of performance improvements, total rewrites of the engines and additional JIT stages added, and public boasts in the official company blogs and marketing material!
Given the disadvantage that it starts at, JavaScript is astonishingly fast, due to the extreme investment in it that you mention. However, in almost all real-world scenarios, it’s still generally pretty easily beaten by ahead-of-time-compiled languages, even if on some microbenchmarks and for a few specific sorts of tasks it can end up competitive with certain of these compiled languages.
>However, in almost all real-world scenarios, it’s still generally pretty easily beaten by ahead-of-time-compiled languages
The claim to be refuted was not "Javascript is faster than AOT compiled languges" however.
Instead, the claim was: "[Javascript is] around the speed of Java and Go in some cases, which are compiled", which is not far off. Especially given that these two are not in general among the fastest kids like C, C++, and Rust.
Yeah, what I expressed was a bit sloppy. Go is AOT-compiled, but kinda the weak link among most such languages as regards performance. Java is somewhere in between the two, and the HotSpot JVM is also generally handily faster than JavaScript engines (it also has had rather a lot of effort put into optimising it, and without most of the starting disadvantages of JavaScript).
The Javascript JIT arms race was the most heavily funded dynamic language arms race since forever - involving three major players (Apple, Google, Mozilla), dedicated teams, tons of benchmarks, constant tracking of performance improvements, total rewrites of the engines and additional JIT stages added, and public boasts in the official company blogs and marketing material!