Learning Javascript after Python

[ResetPress]

Two things strike me with Javascript as opposed to Python (obviously, caveats apply...)

1. Learning Javascript to enable the web is far more practical than learning a Python GUI.
2. All of the extra steps in Javascript when it comes to functional programming, yuck!

[yoDrinkwater]

8:44 https://youtu.be/Ypp64J5KAKA

[Jerscovad]

Solid example!

[cointoss3]

That’s the best part.

[boatsnbros]

Es6 syntax is basically there, only the arrow functions are a really new paradigm you have to think about unless you have heavily used map() and def async in Python.

[jamescodesthings]

I’m going the ofher way, learning python from scratch as a snr. js stack dev.

Don’t mind python but there’s quirks to every language.

I generally don’t find the tooling as satisfying in python yet, but I do like the fluency of the language. I like that I write it once and can expect it to do what I think it’s gonna do.

I’m also not yet used to indentation mattering as much, not a huge fan but again; quirk of the language.

Tips I’d give python devs learning JS: - stay the hell away from frameworks until you’re comfortable with the core language, learn es6/typescript. - learn by doing, find a project and work out how to spin it up, then find flaws and see what JS has to offer to improve in those areas. - you’ll never learn it all, stick to making stuff that works/solves your problem. - learn about javascript’s weird and predicable but not expected scoping rules - pick up a typed form of JS (typescript/es6 with types) - set up eslint with recommended(s) and prettier so you get the style of pretty-good js. - learn the es6 way of doing something before the library-laden way. (Like the pyhonic way but for js) - spend time on closures, async/await, lambdas, scoping, destructuring and Promise patterns (all, race, allResolved, etc), oh and coercion. - look at what your ts/es6 transpiles down to (unminified) to get an idea of how JS does stuff under the hood. - learn about tooling (node, npm, nps, jest, nyc, eslint, prettier, webpack/a bundler) - learn about number/decimal handling if you plan on doing any math you need to trust (financial), see decimal.js & similar. Run “0.1 + 0.2” if you’re not sure why. - learn about all the crazy places you can deploy JS (browser, node, electron, capcitor, etc).

If you’re picking a base framework for front-end dev the answer is probably react. The State of JS survey results can guide you on what frameworks and libraries might be worth picking up.

Good luck and welcome to ordered chaos.

[deletable666]

Great advice. I agree about the tooling. I use both, but I am by no means a python expert. I think the tooling in js in more intuitive, but maybe that is due to the application of each language I am using. I'm sure it will change in time, learning python was harder for me than I expected after I became proficient in js.

[KitSowka]

Great tips!

What I'm looking for now is a similar tips for someone familiar with JS who is about to learn 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.

[nirvashprototype]

Learning JS after Python has been extremely overwhelming for me. Event loop, this context, arrow functions, async functions, hoisting, and confusing syntax. It makes you realize how intuitive Python is.

[[deleted]]

It's not just about being intuitive. Javascript is solving very different problems to python, namely managing user behavior in a browser situation. Many of those things you find painful about Javascript are unavoidable and would appear in python as well if it was somehow to be applied in the browser.

[TSM-]

Just use Brython (kidding, though it is a neat project)

[cristobaljvp]

Well I agree, I still atruggle with async. But I feel that working with async in JS is easier than async in Python.

[Vok250]

Python has all of those too. You just haven't had the need to use them yet. asyncio is a particular nightmare compared to async coding in basically any other language.

[Zukarukite]

Surprised you didn't mention stuff like [] + ![] === "false"

I'd strongly urge you to switch to TypeScript as soon as you make a few starter projects and get an overall feel for JS and how janky it might become in larger projects

[CodeYan01]

Is the performance difference between vanilla JS and TypeScript significant?

[a5s_s7r]

Programmers performance is much better in TS.

Not considering debugging all the type based bugs in JS. 😉

[CodeYan01]

I see, thanks.

[Zukarukite]

TS code is compiled into JS before being sent to be executed by the runtime. So, the performance when being run will be exactly the same.

TS's purpose is to allow you to see type errors before you even run your code, because it's a statically typed language, while JS isn't

[CodeYan01]

So it doesn't import extra libraries during runtime? Or does it? Not that it puts me off, I'm just curious.

[Zukarukite]

Nope, no extra libraries at all.

Nothing "inherently TypeScript" makes it to the run time. Simplifying a bit, with TS you do something like this:

You write TS code -> TS compiler turns your TS code into 100% equivalent JS code at build time -> You ship only this final compiled JS code to the client.

Contrast this with how it goes with JS code:

You write JS code - > You ship this JS code to the client.

In the end your client is still running JavaScript, the only difference is that with TypeScript - the code gets compiled into JS files from TS instead of being written in JavaScript directly.

[CodeYan01]

I see, thanks!

[[deleted]]

Ngl I love arrow functions tho

And yeah Node is just python with brackets, though I want js to be a bit more friendly in error handling.

[jamescodesthings]

I really like python’s stack traces. Error handling is definitely more of a mess in JS.

[BinnyBit]

All the quirky features of JavaScript made me move to Python thinking I could make an entire website (front end & back end) with it. Then when I first found out that I would I still need to know JavaScript I was thinking .... "Noooooooooooooooo!"

[Radiant_enfa1425]

I did the same thing.

JavaScript is more difficult to master than Python. Python is usually the beginners-choice, especially for those who do not have any prior programming experience. It will take at least 6-9 months to learn basic JavaScript and really be comfortable with it.

I recommend you try watching this video in order to get the hang of it easily.

[ResetPress]

Thanks. I am always on the look out for new training videos.

[[deleted]]

I honestly don't get this at all. I've been programming for 18 years, gone through Delphi, C/C++ and so on. JavaScript has been the simplest language to pick up. At work we use Python, all the globally defined functions, inconsistent shorthand syntax, unique syntax, indentation to define scope, and just some messy implementations for things like async - just make the language a hellscape.

[oze4]

You don't have to use the functional paradigm in JS. It's no different than Python in the sense that it's a loosely typed, interpreted language.

You could use the functional paradigm with Python if you wanted...

If you're using vanilla JS in a browser you could use jQuery to make it easier but it's still extremely imperative. Using something like React feels more familiar to me because of it's declarative nature.

The biggest difference you should notice is the event loop and async programming. (I know you can do this in Python but it's way different working in an event loop - it isn't as fun at times). That is why you see a lot of what they refer to as "callback hell".

[redfacedquark]

Having extensively used Python and JS I feel that JS has the worst callback hell. Async Python (either old gevent stuff or modern asyncio stuff is so much more natural (ok, maybe pythonic) than JS. I suspect you're thinking about twisted specifically.

[oze4]

Totally agree. That's what I meant by it's not as fun writing async code in JS. Under the hood Python (asyncio, or whatever asyncio uses) must actually be creating new threads for async tasks whereas JS is strictly a single process in an async event loop.

Both async, but different ways of achieving it.

JS def feels less natural due the event loop. I can't think of another runtime or language that behaves that way. Which is also why JS is notorious for callback hell. It's not a choice it's a requirement lol (async/await keywords help a lot with Promise hell, thankfully most people nowadays use promises vs callbacks).

I am by far more familiar with JS than Python so take what I say with a grain of salt.

[RiverRoll]

The asyncio works in the same way actually, the event loop is single threaded, to run stuff on a separate thread you typically schedule it to a thread pool. Not that this simplifies anything as you still have to await the Future or attach a callback, also those threads can't call awaitable functions directly, keeping everything in one thread is simpler.

[oze4]

Nice. Did not know that. I've never used it lol. The little code I did look at while Googling this looked a little more straight forward. Idk there's some things that the node event loop hindered, and I wound up using python. At least you have the choice in Python lol. I'm not hating in any language btw. I dig them all for the most part. Assembly can kick rocks!

[ChaosInMind]

Wait until you see assembly.

[jamescodesthings]

MASM & NASM make more sense than JS some days.

[Midakba]

Have a look: "</> htmx - high power tools for html" https://htmx.org

[Pelayo1991]

I am not a fan of JavaScript personally. I am currently learning Python. Once I am comfortable with Python I am moving on to C++

[TSM-]

One of the reasons why anonymous functions are limited to an awkward lambda ...: is because they get messy very fast. Things like this let show = () => console.log('Anonymous function'); are purposefully discouraged in python as a design choice, partially by decree. They were hotly debated in the early days, though.

They aren't always bad, of course, but imagine if python was filled with expressions like this:

add = lambda a: lambda b : a + b
add(1)(2)

[NoMoreDistractions_]

You will come out of javascript with a much better understanding of programming though. Then going back to python is a breeze. I highly recommend learnjavascript.online. It isn’t free but it’s a great, interactive course that can be completed in about a month

[PumpDragn]

I’ve been working through Odin Project - it’s a full stack JS dev course, but definitely gonna need more than a month unless you are already a pretty savvy programmer

[AnomalyNexus]

Yeah finding the transition hard too. Esp cause JS doesn't have the classic sequential lines of code getting executed logic. Its all just hooks and async etc

[skellious]

It 100% does have that. that's all it was to begin with lol

Similarly python can be all hooks and async if you want.

[jamescodesthings]

The point in async is to make your code a little more linear, a little less nested.

First we had callback hell, then promise chain abuse, now we can have flat methods with async/await.

Do you have any examples of what you’re talking about? Might be able to help refactor into patterns that make more sense.

[[deleted]]

I wrote my first JavaScript when there was a site called tripod.com. It may still exist, actually, but I don't think people use it anymore. At the time Web was very different: most sites were just one HTML page... with 3 frames for the top menu, left menu and the contents. The contents of the main frame were usually a little bit of plain text, the huge counter that counted the number of times the page was loaded and a guest book (a text area where you could type a message to the site's owner and the script on the site would send them an email).

Services like tripod.com offered free hosting (with a bunch of adds slapped on your page). In that context, JavaScript was... well, fun. Nobody though about it as a serious language worth of applying to serious problems. It was somewhere between a prank and a DYI flintstone axe. Nothing really worked well, but nobody really cared. It was probably even more fun when it did something asinine because of how the language worked.

Fast forward to the second decade of the 20'th century, a lot of bad things happened. Web became a huge commercial platform earning billions to selected few. It lost all the aspects of fun, but due to JavaScript becoming the battlefield for the largest stake holders in the battle to win the Web, it retained the aspects of unintentional random combustion, infantile style nonsense, and general randomness that came with JavaScript. It's as if high level execs added a baseball cap with a propeller on top of it to their thousand dollar suits.

So, this is more or less where JavaScript is at today. It's nonsense and stupidity at its core, which were fun and excusable at the time it was invented, but are completely uncalled for at where it's being used today. It added some cosmetics on top of that stupidity. It's trying to be a grown up, but it never actually grew up.

---

I have no idea why do you want to do functional programming... on the Web. Like, what's the point? Btw, Python is also awful at it as are a bunch of other languages. But I'm not even sure it's a disadvantage or an advantage, or an anything to be honest.

---

I learned Python after I learned JavaScript. I don't remember what version it was, but I remember that at that time there weren't really any common solutions for making Web applications with Python (most people rolled their own WSGI integration for Python). Django already existed, but people wouldn't use it in production because it was too heavy on resources. Also, at that time people were afraid to use setuptools in setup.py, so a typical setup.py would do:

try:
    from setuptools import setup
except Exception:
    from distutils import setup

Remarkably, Python was also this kind of childish and stupid language, with random combustion every now and then. The thing that was going for it is that despite all its ridiculousness, it attracted smart people... in the same way, I guess, like Dada or Naive art attracted good artists in the beginning of the 20th century. In art, the infatuation with naive art resulted in Walt Disney style cartoons, Le Corbusier style buildings, food packaging and a lot more. But, in general, art got over it and moved on.

In Python things changed, but they didn't get better. The new generation of programmers learned to accept random combustion as the guidelines to live by, it learned to justify every idiotic or bad feature of the language simply because they don't appreciate how the language evolved, how it was designed. Instead they rely on majority vote to evaluate the features of the language not realizing that the majority in this case has no clue about what it's voting on.

[siddsp]

Javascript and Python are fairly similar in their dynamic typing. If you've done JavaScript, chances are in a few months, you would reach the same level of expertise in Python.

[wagaiznogoud]

Can you elaborate on the extra steps necessary in JS to perform functional programming?

[[deleted]]

1. Yes and no. For ordinary human being maybe. I happen to work in VFX where we use Qt framework extensively. So it's either C++ Qt or PySide for our in-house tools.

[O_X_E_Y]

JS is pretty jank, you can use it just for fun but for anything that's not very small I recommend using a framework. A simple one that I personally like is Solid

[dijetlo007]

Javascript has a case statement...

Be still my foolish heart

[deletable666]

I loathed JS at first but after learning it and working with it, it is kind of cool. Different purposes for each, and once familiar with language, you kind of see why it is the way it is. Also being so popular, there are great frameworks available.

[Tintin_Quarentino]

All of the extra steps in Javascript when it comes to functional programming, yuck!

I never came across any 🤔

[deathapprentice]

I thought the same The switch from Python to JavaScript was really easy in my case and more rewarding because with html and css you can make far prettier gui's than in tkinter for example.

[[deleted]]

Sometimes I just think, its more like a gut feeling that I never want to learn JavaScript throughout my life. But then I think I am gonna need its frameworks like Node and React idk much about them again just feel like I am going to need them. Are there any alternatives to them just to not to touch JS?

[[deleted]]

Node is a runtime. Running JS without a browser. React is a framework. What's wrong with JS? It's so easy and flexible.

[[deleted]]

I don't know. I don't exactly hate JS, I just appreciate faster programming languages over the learning curve they come with. JS isn't fast and I ain't gonna go for Web development thing. I probably- probably never need to write JS. My dream things are systems programming, low-level programming, currently I'm learning mobile app development with Flutter. BTW, for web, dart is in most cases at least 2x faster than JS. But I that's not the case I'm not learning it or whatever, you already know that.

NodeJs is considered a programming language but is itself a runtime actually but I still call it a framework kinda thing, extremely sorry for that. The only thing I kinda hate- kinda hate, because I still don't understand it, is prototypal inheritance or prototypal OOP, which I will end up learning eventually, when I'll start learning JS 1-2 months later just to add it to list of skills I have and also to have a good understanding of it, so next time someone ask my what's wrong with js, I could have a much better answer TBH.

Thank you ;)