5 JavaScript Tips You Probably Don't Know

We do a lot of TypeScript on this channel, but JavaScript is still a growing language, and you can do some pretty cool stuff with JS these days! If it's been a while since you looked at what's new in JavaScript, you might find something new in this video!

#javascript #ecmascript

[fagnersales]

Wouldn't it be possible to create a 2d Array using `Array.from({ length: 5 }, () => [])`?

[dimitro.cardellini]

2d arrays:
const a = Array.from({ length: 5 }, () => []);

range:
const rangle = (start: number, end: number) => {
const [length, step] = end > start ? [end - start + 1, 1] : [start - end + 1, -1];
return Array.from({ length }, (_, index) => start + index * step);
}

[mluevanos]

I like creating array like this: Array.from({length: 10}, (_, i) => i)

[dechobarca]

Oh damn, #4 is really tricky that it behaves the way it does to be honest. I mean maybe not according to the language specification, but I can see a lot of people accidentally slipping before/unless they test their code, myself included.

Thanks for the video, really cool one.

[Mane]

I am really loving these JavaScript videos. Today everything is about TypeScript and while I love using and learning about it, it sometimes doesn't help you with solving a problem. You need to understand the underlying language (JavaScript) and these videos are helping to learn about some of the more modern features and APIs that JavaScript offers. Then in conjunction with TypeScript, you get superpowers.

[mateuszgroth]

The array fill caught me off guard once during an interview for a job. I had to do some kind of algorithm, which I actually coded the right way, but I initialized the array like you showed and it screw me over. I learned it the 'hard' way unfortunately ;D

[JaimeOlmo]

Map and Set, I would love a video about this topic.

[Jambajakumba]

Wow really cool video. I didn't know about a bunch of these additions Andrew. Thanks!

[MrREALball]

Didnt know you could do this type of thing with bind. Would use it in my code now, probably.

[todd_matheson]

It's much more performant and better to use `Array.from({ length: 5 }), () => [])`. It's more concise and it only iterates once over the array which is much better for larger arrays. Also, the second argument to Array.from, the initializer function takes 2 arguments, the seconds being the index, so that comes in super handy sometimes too.

[joostschuur]

Completely unrelated, but what is going on with that 'fi' font ligature? Curious that that isn't monospaced but everything else is?

[Luxcium]

I am sorry I do not understand the *declare* keyword purpose on line 2 when you explain the _NCO_ @ 2:00 ... or in any other cases where you have been using it in the examples...

[DontFollowZim]

Only the 2d array tip was new for me, but also probably the least useful since I can't remember a time where I ever created a set size 2d array without looping over data that needs to get injected into that array anyway...

[SomewhatLazy]

5 JavaScript tips... in TypeScript. Great job.

[majorhumbert]

If you work with immutable data, it won't be a problem to instantiate arrays like this.

[PickledHam]

just wondering when you were a teen if you are from winchester, tn . you look familiar

[thematrix]

Rather than doing new Array(x).fill().map(), I think [...new Array(x)].map() is nicer to read. Don't know the exact performance implications of spread vs fill but I only ever use it for small arrays so I'm sure it's negligible

[montebont]

The title is misleading, The video is about Typescript and not about Javascript.

[tbigqhb]

Just stop doing functional and mutate your state

[aidemalo]

>5 JavaScript Tips
Proceeds with TS, dislike