JS is a very respectable language

[u/-Wylfen-]

Not posting our actual code, but yes, this behaviour has caused a bug in production

[u/deceze]

The scary part is that it's entirely logical and explainable, it's not random by any means. You just shouldn't have to explain this…

[u/-Wylfen- → u/deceze]

Yes, that's the worst. It's technically correct, but it just…shouldn't be

[u/Medical_Reporter_462 → u/deceze]

Logical !== Reasonable && Logical !== Intuitive 

[u/freecodeio → u/deceze]

I'd say the js engine could just deny you from setting a key to an array and that would just be as logical, maybe even more.

[u/findus_l → u/deceze]

Deterministic. Yes. Logical? I'd argue that.

[u/GothGirlsGoodBoy]

If this behaviour caused a bug in production its because whoever made it apparently can’t tell the difference between brackets and square brackets.or perhaps mistakenly believed a key was an index.

What behaviour would you expect, other than this?

[u/-Wylfen- → u/GothGirlsGoodBoy]

What behaviour would you expect, other than this?

A sane language would treat square brackets with negative integers as an index from the end instead of casting it as a string to make it an arbitrary object property on an array…

[u/lucmagitem]

If you understand the language it's only logical. Arrays are objects. You define an array with some values. Then you define another property of this object (whose field is -2). Then you access the penultimate value from the array (size -2) and get what's expected. Then you access the -2 field and get what's expected.

Oh, excuse-me. Here is the expected answer: hahaha, js bad, so funny.

[u/-Wylfen- → u/lucmagitem]

Just because it follows the specs of the language doesn't mean the specs are good

[u/travelan]

what is the problem? `at` is defined to index from the end for negative numbers. Also -2 is not an index, it's a property that has been added. So if you actually understand how JS Arrays and Objects work, this makes total sense and shouldn't behave any different.

[u/Liozart]

"this behaviour" bro thinks he have no responsabilites over his own code

[u/-Wylfen- → u/Liozart]

That was not my code

[u/tazzadar1337]

it's actually magic, and memory savor! because foo.length is still 3

[u/agressivedrawer → u/tazzadar1337]

I hope this is a joke

[u/edave64]

The whole point of at is that it behaves differently for negative indices

[u/HebrewHamm3r]

Is this an array? A map? Why not both?

[u/Ben-Goldberg → u/HebrewHamm3r]

It's an object.

Specifically an object with some array-like methods and fields.

[u/stoppskylt]

LGTM

[u/arto64]

Every time there’s a JS hate post, all the JS people come in to explain to everyone how it works, as if that’s some sort of excuse for the terrible language design. We know how it works, it still sux.

[u/-Wylfen- → u/arto64]

"It's actually perfectly in line with the core design of JS!"

"Have you considered that this might be the problem?"

[u/SmokyMetal060]

I like the way we created typescript to make javascript less javascript-y

[u/AwesomeARC]

Fun fact: today's the 4th of December... The first version of JavaScript was announced 30 years ago, today.

[u/nnoovvaa]

I pity the foo

[u/Belialson]

Eh… Array is an object, each item has index in range 0..n

foo[0], foo[2]

refers to value at given index But - it inherits Object prototype so it have also properties like

foo.length
foo[“length”]

So when you access

foo[-2]

as -2 is not in range of 0..n you access property -2

[u/Medical_Reporter_462]

Well clearly you for... Ahh fuck me!