[umanwizard]

Facebook has almost certainly the world's largest codebase in any PHP-family language (Hack, which is essentially PHP + gradual typing + a better standard library, but still very much PHP-flavored). The code is fine.

Part of the reason is the improvements of Hack over PHP, part of the reason is very aggressive linting (to, e.g., enforce the use of types), and part of it is probably that Facebook doesn't hire for "PHP positions", but for generalist software engineers.

[eeZah7Ux]

Facebook indeed does not have the same hiring bar as "$company php (sweat)shop".

However, all the other companies align themselves to the level of the average candidate they can hire.

The quality of the library ecosystem in both js and php is a good measure of that level - sadly.