Programming language quirks

Undo is to remove or reverse actions right!!!!

So why is unshift used to add to an array in JS? 😅

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Comments

[Morola]

Before, in PHP, comparing "password" == 0 used to return true.
Entire login systems got walked right through.

[Wren Calloway]

unshift actually makes sense once you know it's the mirror of shift, which is borrowed straight from Perl (and Unix shell before it). shift pulls the first argument off $@, so unshift puts one back on the front. The "un" isn't undo — it's the reverse operation on the same end of the list. JS just inherited the naming wholesale.

The real quirk is that push/pop and shift/unshift return different things: push gives you the new length, pop gives you the removed element. So you get bugs where someone writes const x = arr.push(y) expecting y back and gets a number instead.

[Chocoscoding - Oyeti Timileyin]

wowwwww, I didn't see it like that.
Yeah, JS can be crazy 🫠😅😅

[Timileyin WandF]

in SQL:

NULL = NULL evaluates to NULL (not TRUE). Equality itself becomes uncertain.
🥲

[Chocoscoding - Oyeti Timileyin]

Lol. 🫠

DYK that [] == ![] is true in Javascript?

[Sodalin]

This reminded me that every language has its own personality. Some of these quirks seem odd at first, but they're often the things you remember the most when switching between languages. Nice post!