I wish people would stop saying "JavaScript was written in 10 days" with the subtle implication that this is somehow shoddy or half-arsed. GvR wrote the first version of Python in a month in December 1989; the first bit of C was made out of B and NB in a month or two in ~1970. Every single bit of software you've ever used that isn't some enterprise nightmare was first a proof of concept hacked together in a couple of weeks by whoever first did it. This is entirely normal; it's not a bad thing!
@sil it’s not that hard to just make stuff, but management in companies are sold the idea that it’s really hard and dangerous to let your own engineers build stuff, so they pay through the nose for a second rate SaaS solution that does the easy bit poorly, and where their engineers still need to do the hard parts (but now complicated by having to work via the third party thingy).