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5 neat JavaScript tips

Dalibor Belic on March 21, 2021

In this post, I'll show you 5 neat JavaScript tips that will help you become a better developer. Although this post requires some knowledge of Java...

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Kazppa • Mar 21 '21

May i ask some explanation about the "benefits" of destructuring ?

Akash Kava • Mar 22 '21

Destructuring improves speed by accessing members by one time assignment. Every a.b member expression is slower as it travels prototype chain for access.

The argument becomes immutable, reassigning destructred variable will not modify the source.

Kaleb M • Mar 22 '21

I don't think this would be true if the destructured key was an object, it would still be by reference.

Overall I agree that destructuring is cleaner though!

Akash Kava • Mar 24 '21

const user = { name: "Akash" };
let { name } = user;
name = undefined;
console.log(user.name);

Should it print undefined or "Akash"?

In no way destructured variable is by reference. Reassigning destructured variable is immutable (not changing property of object held in destructured variable if it is an object).

Kaleb M • Mar 24 '21

Yes, you assigned the string, so no not by reference. If name itself was an object, it would be by reference yea?

Akash Kava • Mar 24 '21

Try it and show me a working example.

Blake Campbell • Mar 21 '21

I had no idea you could style console.logs, that's amazing!

Dalibor Belic • Mar 21 '21

Yep, pretty neat! :)

matgott • Mar 22 '21

Destructuring isn't working "with reference". This could be confusing.

Objects in Javascript are mutables, so if you are destructuring an object which one of it properties is another object, the variable created for that property will point to the same object in the Heap.

Riaan Pietersen • Mar 30 '21

In the days of ActionScript we were able to use a "with" statement.. kirupa.com/developer/actionscript/...

Is there something similar in JS?! I wonder.. :)

Benjamin Van Ryseghem • Mar 25 '21

obj.key is undefined, isn't it ?

pris stratton • Mar 21 '21

The callback into Promise one is so handy. It means you can use async await as well which is so much easier to write.

CodenameCookie • Mar 21 '21

There is a typo. You wrote 'trase' instead of 'trace'. Good article though.

Dalibor Belic • Mar 22 '21

Tnx!

Mafee7 • Mar 22 '21

Thx For the tip!

Dalibor Belic • Mar 22 '21

Welcome!

Jon Portella • Mar 24 '21

FYI there's a Node.js util that does the promisifying for you, you don't need to write your own. Thanks for sharing!

Mihail Malo • Mar 25 '21

And a lot of nodejs builtins come in proper promise versions now, not by making you promisify them in userspace!

require("fs/promises").readdir('.').then(console.log)

Hurrah!

Ali Taha Shakir • Mar 22 '21

What if I have 15-20 elements which I need to show in component, is it good / good practice to destructure 20 elements as arguments?

Dalibor Belic • Mar 22 '21

Yes! In that case, I would do the 2nd version: function (tiger) { ... and then inside the function: { endangered, latin, ... } = tiger