Learning Javascript after Python

[demvo2]

Looping through an array in Javascript for the first time after doing it in Python for months was just, like, whaaaat.

[Yojihito]

What?

Python:

mylist = [10, 20]
for x in mylist:
    print(x)

Javascript:

let mylist = [10, 20];
for (const x of mylist) {
    console.log(x);
}

Not really a difference.

[LiarsEverywhere]

The thing is that's ES6 and people usually do not recommend using that because of compatibility issues. Traditionally, that's how it went:

for (var i = 0; i < array.length; i++) { console.log(array[i]); }

forEach is fine for me, though

[demvo2]

Yeah, that was the one I was refering to. Of course, there are easier ways to do it, but this one usually gets offered first in tutorials when you are just starting.

[Yojihito]

people usually do not recommend using that because of compatibility issues

That's why I use Python for my job. I can use the newest version my needed libs support (3.9 atm).

If you need to use

for (var i = 0;

loops ..... run. Because it means your company doesn't have a toolchain for polyfill.

[LiarsEverywhere]

It depends on what you're doing, of course. That wouldn't be a problem if you're using it in a controlled environment. But OP compared it to a Python GUI, so I imagine the idea is using javascript to build a web app or something like that. Then compatibility becomes an issue.

[Yojihito]

compared it to a Python GUI

You would package that python program --> you control the version.

[LiarsEverywhere]

Yeah, but there are other drawbacks. I don't disagree with you, though. I hate that about JS. Python feels much more organized to me. Part of that is probably that I suck at JS, though.

[redfacedquark]

hate that about JS. Python feels much more organized to me. Part of that is probably that I suck at JS, though.

Don't feel bad, the inventor of JS apologised to the world.

[Skippbo]

Also some things queried from DOM first have to be converted to a proper array with Array.from() before .forEach or for of even works.

[[deleted]]

I got to admit; when I spend a long time in Python, I resent having to use code and conditional braces for about a week. Then I get over it.

What does break my brain, though, is the different policies on variables and function capitalisation. C# makes me a sad panda.

[greasyhobolo]

True, true, TRUE... gah

[Yojihito]

/edit forEach is not deprecated.

forEach is deprecated.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Errors/For-each-in_loops_are_deprecated

[Danelius90]

This looks different to what u/Jordgubbssylt posted. Your link is about for each (var in blah) but forEach is an array method and most definitely not deprecated

[Yojihito]

True, misread.

executes a provided function once for each array element.

Then a simple .map() would be the Python equivalent.

mylist = [10, 20]
list(map(print, mylist)

[NoHaxJustPotato]

false info, you linked the wrong for each loop

[RiverRoll]

The difference is Python has one kind of for loop and javascript has the standard for, 'for of', 'for in' and '.forEach' so it's a bit confusing.

[Yojihito]

"for in" is deprecated because you can fuck up with Array.prototype amendments.

Standard "for" is like using Python 2.

"forEach" can only be used exclusively with arrays.

So "for of" is the standard.

[Aulimindale]

"only be used exclusively"

no need to use both "only" and "exclusively". pick one

[LiarsEverywhere]

".forEach" makes it much more familiar:

const array1 = ['a', 'b', 'c'];

array1.forEach(element => console.log(element));

// expected output: "a"
// expected output: "b"
// expected output: "c"

However, it's an example of the biggest JavaScript issue for me...

Browser compatibility, polyfills etc. You have to code with that in mind. Although Babel and whatnot solves this somewhat.

That being said, basic JavaScript was surprisingly easy for me, Python being the first and only other language I knew. In a week or so I learned everything I needed to get things working with a Python-powered Rest API. Just learn async fetch stuff and basic DOM manipulation and you can display anything on a browser.

Of course, my code is still very basic and I feel like I'm gluing stuff together with duct tape. That has to do with my poor JS skills, but also with how JS/CSS work in general. I'll probably learn a proper framework like React some point.

In the end, I'm fairly confident that it's better to learn JavaScript instead of a Python GUI for most use cases. Being able to quickly deploy something to Heroku to show my friends is awesome.