I wrote my own interpreters for my own languages, including stuff used in production. 10 days for designing and implementing something like JavaScript is pretty

I wrote my own interpreters for my own languages, including stuff used in production. 10 days for designing and implementing something like JavaScript is pretty good. Also, I think that the number of problems in JS normalized by the time it took to make the first version (and that time limit was due to a deadline that the creator did not choose) is very likely smaller than in many, many other languages, if not all the remotely popular ones.