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5 easy wins for cleaner Javascript code 🧹

Mikhail Levkovsky on August 27, 2019

Imagine an empty and clean kitchen sink. It's so shiny you can see your reflection inside of it. If you had a dirty plate, you would probably feel ...

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James Thomson • Aug 27 '19

Also, use Promises properly. Don't nest Promises, use the chain to call other functions.

e.g.

function getCall () {
  return new Promise((res, rej) => setTimeout(() => res('success'), 2000))
}

function doSomething () {
  console.log('do something else')
}

getCall()
  .then(res => console.log(res))
  .then(doSomething)
  .then(() => console.log('done'))

jsfiddle.net/jamesbrndwgn/4sxty91n/1/

Also, make use of async/await.

Mikhail Levkovsky • Aug 27 '19

For sure! I have a whole other article coming up on how to clean up promises :)
Thanks for sharing

Ezell Frazier • Aug 27 '19 • Edited

Is it me or does the advice more-or-less pertain to modern code over 'clean' code?

Don't get me wrong or anything, I like the article and agree with it. However, I'm not going to consider a basic for-loop not 'clean'.

I guess my point is, I'm beginning to prioritize readable code over modern syntax. At my last job, ES6 was completely alien to the team. Everyone was comfortable with writing JavaScript from the mid-late 2000's, with JQuery sprinkled in.

The use-cases never called for more modern syntax.

So when I came along, I still tried my best to build with the 'lowest common denominator' in mind. Should it have to be that way? That's another conversation, but I'm not sure if I'd lump modern syntax and clean code together. The truth is always in the eye of the beholder. If a junior dev can understand what's going on, I'd consider it clean enough.

Mikhail Levkovsky • Aug 27 '19

I find Javascript and Typescript really try to move towards being as succinct as possible. Sometimes it's a good thing, sometimes not.
I agree that you don't always need the fanciest bells and whistles to get the job done, however it's always nice to learn new things.
Which is why when people say they don't like Typescript because you don't get all the new ES features right away I kind of shrug, because I don't need them.
For loops are fine, I just thought it's important to demonstrate the difference between a 'for of' and a 'for in'. I think using the right type of syntax for the right job and use case is super important.

Mikołaj Romanowski • Aug 27 '19

Actually, your 3rd point is wrong. I dont know how Typescript would behave, but as for JS what You do in second example is assigning variable user to new object. And You loose properties set by User constructor

Mikhail Levkovsky • Aug 27 '19

You’re absolutely right! I forgot to type it! Will update the gist shortly. Thanks for the catch

🇨🇵️ Nathan Graule • Aug 28 '19

It's not only about Typescript typing; TS is right about changing the type of your variable because you're assigning a completely new value to it. Doesn't matter if it's an User object, or a string or a number, she the assignment, user is an object with the specified values in it. The User prototype is lost.

Akash Kava • Aug 28 '19

VSCode with TSLint with auto correction does more than given examples ...

Mikhail Levkovsky • Aug 28 '19

Yes of course an entire linter does more than 5 things but a linter is the how and not the why
I think it’s important to demonstrate and explain why we lint certain things and what those rules do.

Akash Kava • Aug 29 '19

For most part, I am not interested in learning why, I am sure people who made TSLint definitely had better understanding, and when you are working many people on team, explaining why would be extremely time consuming and unimportant job. This is the reason, there is only one captain in the team and if captain says use TSLint, follow and do the right job.

Mikhail Levkovsky • Aug 29 '19

We’ll agree to disagree. Personally I never find it a waste of time to explain (or learn) the why. It helps people become better devs and tune the tools they use to their needs.

Ben Sinclair • Aug 27 '19

Your first example has the same code snippet for both the "good" and the "bad" version. I think you pasted the wrong one.

Mikhail Levkovsky • Aug 27 '19

Not exactly :)
In the first example I use var, and in the second I use const
But I guess the example isn’t clear, thanks for the feedback I’ll update it

Ben Sinclair • Aug 27 '19 • Edited

In the first one you use const, and in the second one you use const!
The only difference is a line of whitespace.

Actually, looking forward, they're both really the snippet for your "for in... for of" comparison later in the post:

Mikhail Levkovsky • Aug 27 '19 • Edited

Wow that is super weird! The gists seem to be rendering out of order :/
Check the screenshot to see what should be there.
I wonder if there's anyway to get support on this from dev.to about this
Can you refresh the page please to see if it's still out of order?

Ben Sinclair • Aug 27 '19

It's working now :)

Mikhail Levkovsky • Aug 27 '19

Thanks for flagging btw
FWIW I added a disclaimer to the top of the article to give people a heads up. So strange

Joep Meindertsma • Aug 27 '19

Instead of trying to remember all these, you could use a linter with some sane linting configuration. That way, your editor will tell you whenever you're using a var or have unmerged imports,

Mikhail Levkovsky • Aug 27 '19

100%. Although I’m not a fan of angular, their linting rules is usually what I follow. This article tries to also demonstrate the why behind the how. I think just slapping on a linter without understanding why isn’t very good

The Black Mamba🔥 • Aug 27 '19

The example snippet for second snippet is actually of the 4th point

Mikhail Levkovsky • Aug 27 '19

Something really weird is going on with the way the gists are being rendered. They seem to randomly show up out of order :/
Would you mind refreshing the page and seeing if it's still like that?
Thanks

The Black Mamba🔥 • Aug 27 '19

Weird, now it's showing correctly

Mikhail Levkovsky • Aug 27 '19

Ya thanks for flagging it. I put a disclaimer at the top of the post. Super odd

Arun Kumar G • Aug 27 '19 • Edited

What about arrow functions? and Async Await, I felt they should have been here.

Mikhail Levkovsky • Aug 27 '19

Hey Arun

Thanks for taking the time to read it :)
I agree Async/Await and arrow functions are game changers.
I have a few more articles coming up so stay tuned and I'll make sure to cover those topics. There's also these other posts you might find interesting that I have written

Ardalan • Aug 27 '19

about first things im not sure but another was good.

Seanmclem • Aug 27 '19

Are the examples for one and five supposed to be the same thing?

Mikhail Levkovsky • Aug 27 '19

No, there’s a super weird thing going on where the gists render out of order or get duplicated. No idea why :/
Just refresh the page and it should be good

Dennis Keirsgieter • Aug 27 '19

Your second example seems to be the same snippets as the first? For var/let instead of the string template.

Mikhail Levkovsky • Aug 27 '19 • Edited

A few people have mentioned that the order of gists is all messed up, and sometimes the same gist is duplicated. not really sure what's going on :/
If you refresh the page it usually goes to the normal order