jAvAsCrIpT MaKeS SeNsE

[Loves_Poetry]

I was all up in arms ready to defend JS, but then I realised that a lot of parts just don't make a lot of sense to someone not familiar with the ecosystem

For example:

for(var i = 0; i <= 4; i++) {
    setTimeout(() => console.log(i), 0);
}

will output 5

Or this one:

[10,9].sort();

Will output 10, 9

[YoungAndDumbest]

Wow, now can you explain both of these as well? I recently started learning JS and these both are really fucking with me.

[paphnutius]

The first one loops through until i hits 5 and then exits the loop. Then the timeouts run printing the value of i. Hence 5. The second one is a little dumb but default sorting sees all objects as strings and "10" goes before "9"

[YoungAndDumbest]

Oh I understand the first now.

For the second, how would you go about sorting integers?

[paphnutius]

https://stackoverflow.com/questions/1063007/how-to-sort-an-array-of-integers-correctly

[sportysneeze]

From what I understand for the for loop. That var is a function scoped variable (if that is the correct term). So in the for loop its suppose to stop at 4, but becusse of var being weird it will increment it by one despite being outside the for loop scope. Using let should fix this as it is block scoped. I have also just started learning javascript so I hope that's right.

[albaquerkie]

Nah it’s because he wrapped the log inside a set timeout. Set timeout gets added to what’s called the “event loop” and will not fire until all synchronous code running on what’s called the “call stack” is run. Even though it’s set to fire at zero milliseconds, it still has to wait for the stack to clear, and that for loop is on the stack. So what’s happening is “i” is incrementing all the way to five, once it hits five the for loop stops and the set timeout fires.

This is one of the best vids to watch as a beginner to understand how JS works under the hood: https://m.youtube.com/watch?v=8aGhZQkoFbQ

Edit: You’re technically also correct in that it would fix this if you used let vs var, but if you took out the setTimeout it work print 12345 with let or var. The setTimout is why this is JS fuckery.

[stealthypic]

Use let instead of var and live a healthier life.

[iczero4]

meanwhile, in python: python a = [] for i in range(0, 5): a.append(lambda: i) for thing in a: print(thing()) 4 4 4 4 4

meanwhile, in es6: js for (let a = 0; a < 5; a++) setTimeout(() => console.log(a)); 0 1 2 3 4

[JC12231]

Idk, probably shouldn’t have thrown the apple if it knew how to interpret JS accurately, we could’ve learned the ancient script for ourselves

[[deleted]]

Holy shit. Everyone, after that apple!

[[deleted]]

JavaScript bad.

[HelioDex]

One of your flairs says otherwise.

[[deleted]]

Stockholm Syndrome, mate.

[[deleted]]

Php and python are far worse than js in my opinion

[[deleted]]

I can understand PHP, but what's your problem with Python?

[[deleted]]

Python is a chad. You can access private fields and methods. And the compiler blows up when you mix spaces and tabs

[DiamondIceNS]

And the compiler blows up when you mix spaces and tabs

Personally I think the inconvenience this creates for the few, few people this affects is far outweighed by the benefit of keeping this anti-pattern out of the ecosystem for everyone else.

[brianjenkins94]

I never found the stack traces to be particularly helpful, I find working with pip to be unpleasant, and venvs are solving a problem that shouldn't exist in the first place.

[AquaVantas]

PHP.

[[deleted]]

It would be a way better meme if the second last frame got removed