[G.....n]

Use named functions. They make stack traces a lot easier to read.

#dobrarada #javascript

[G.....n]

When something is intentionally missing or removed, set it to null.

Don't set things to undefined. Reserve that value to mean "not yet set to anything."

[Marmite]

@Ginden: Oczywiste rady są oczywiste, ale z drugiej strony ludzie faktycznie zbyt rzadko je stosują.