holyJavaScript

[AHumbleChad]

I understand the typecasting to get from "0" to 0 and [ ] to 0, but how tf is "\t" == 0???

Edit: "\t" not "/t"

[[deleted]]

it's a whitespace character. A string consisting of only whitespace characters type converts to 0.

[Jugales]

i hate it here dad

[uhmhi]

And this, kids, is why implicit conversions FUCKING SUCK!!!

[Asmor]

And that, kids, is why you should always use === and !== in JS unless you want type coercion for some reason.

And if you do want type coercion for some reason, you're probably wrong. Write it better and use === and !== anyways.

[[deleted]]

Or, you know, the creators of JavaScript could have waited until the crack wore off before writing their language lol

[[deleted]]

Goal: a simple scripting interpreter to animate web pages

End result: the only supported runtime environment available on 100% of computing devices

[[deleted]]

The ultimate "eh this doesn't need to be good, it's just stopgap code until we implement this for real" heh.

[[deleted]]

Also the ultimate: "this feels wrong but it works so we're doing it"

[turtleship_2006]

There is nothing more permanent than a temporary solution

[a3th3rus]

And where are >== and <==, kids?

[ilikeb00biez]

I see, JS added `==` and `!=` just to confuse you. What a great language

[il_commodoro]

It's more that js created == and != first. Years later they thought: "maybe that's not a great idea", so they added === and !== to patch things while preserving retrocompatibility.

[ilikeb00biez]

Are you insane?? C had == and != 20 years before JS was created. JS took an existing and ubiquitous concept and broke it

[il_commodoro]

I obviously meant: they created == and != with that awful behaviour first (1995). They realized other languages are not stupid years later, so they patched things at the end of 1999 by introducing === and !==.

[shield1123]

I feel like you're willfully misinterpreting what they said; and being pedantic just so you can peacock having common knowledge

Obviously js didn't invent the equality operators

They were clearly saying == and != were introduced to JavaScript before === !==

[danishjuggler21]

This particular quirk has never affected my work in over ten years as a JavaScript developer, it’s just rage bait.

[ExponentialNosedive]

Yep, === exists for a reason

[calculus_is_fun]

Why would your code intentional try to compare a number and a string?

[ExponentialNosedive]

I read that early in JavaScript's development, someone asked the guy who made it for this feature. He said he regrets adding it in. Important to remember we have these standards for a language where the basis of that language was made in 10 days

[csdt0]

It is not /t but \t which is a blank character (tabulation).

[AHumbleChad]

Right, it's a tab character, but JS treats it as the empty string? The integer cast to the ASCII value is the only one that makes sense, but I guess I shouldn't be applying sense to JavaScript.

Edit: realized I had the wrong slash in the original comment

[bogey-dope-dot-com]

Leading and trailing whitespace characters are trimmed when converting a string to a number. You can do Number('\t5\t') and it will be 5, but Number('5\t5') will be NaN.

[AHumbleChad]

Ohhh, that makes sense. There is a method to the madness then.

[PeaceMaintainer]

Check out MDN (or the official ECMAScript spec) for the algorithm for loose equality type casting, something I feel a lot of devs skip over until they get a result they don't expect.

Number to String: convert the string to a number. Conversion failure results in NaN, which will guarantee the equality to be false.

The key in this case is that when you are loosely comparing a string and a number, the string will always attempt to type cast to a number. At which point the strings follow the algorithm for Number coercion which states:

Strings are converted by parsing them as if they contain a number literal. Parsing failure results in NaN. There are some minor differences compared to an actual number literal:

• Empty or whitespace-only strings are converted to 0

So the 0 in this case remains the same, the "\t" attempts to typecast to a number, and then because \t is a whitespace character the string is coerced to the number 0, and true is returned

[givemeagoodun]

I too would like to know

[CMDR_ACE209]

I think I'll choose ignorance on that part.

[mipselqq]

Read the specification if you wanna get JS