TFA references a post that states that optimized switch statements in V8 are still just if-elseif-else and not jump tables, at least back when it was written. They might be faster than unoptimized JS, but certainly not as fast as jump tables. The author didn't even bother to split up the functions/switch blocks further when they learned about the requirements to get V8 to actually optimize a switch, as it seemed not worth it.