5 Must Know JavaScript Features That Almost Nobody Knows 

Or you could just use your classes and datatypes correctly.

@@neuralwarp yeah why use a feature that saves times

Yea for me also

I love you `?.`

As dangerous as using 'goto' in a high level language. Almost all of these will cause hard to debug bugs sooner or later . Just use a strongly typed alternative.

The problem with the first way is that, according to the ECMAScript spec, a SyntaxError will be thrown if the function body has a "use strict" directive.

I am still surprised at how underused destructuring is everywhere in javascript today in favour of dot notation. I never understood why it never caught on. product.title, product.price? does that help with the readability or is it useless repetition.

X = (assert something) ? Val1 : (assertion 2) ? Val2 : val3;

yes,,, so true!

This ?? thingies is amazing...

and its basically a ternary operation. object ?? val1 looks very similar to object? (as in, does it exist) ? val1 : val2

language = 'Python' if is_readable else 'Javascript'

thank you :)

I found out when I opened devtools in facebook, they had a warning not to paste any malicious code into the console.

@@MrBroady02 Same with discord but I didn't know how it was done

Does he have a full JavaScript course on udemy? If so can someone pls help me with a link or his name on udemy?

@@Manny-mc3rx I don't think so but on fireship.io

Another cool thing you can look up is that you can put images in the chrome console

I'm surprised he didn't put it in the video, but console.dir() is another great feature. Makes it super easy to see heavily nested JSON in the terminal

@@Rogue_Art Oh interesting, I'll be giving that a go!

Lol, same thoughts. I thought there would be some new syntax for function call like that: function?() or array index array?[571]

And I don't like private property syntax like #privateProp, "private" keyword or _privateProp would be much better

@@SirusStarTV execution function by "function()" is just a sugar syntax for "function.call(thisArg, args)" so it's quite the same as with object properties "function?.call(thisArg, args)" -> "function?.()"

Felt the same thing. Console.log styling was jaw dropping.

same

I have to add that I still haven't used it :P

Same boat. I was aware of it though because many sites like discord will spam styled logs to get people from not using the devtools if they're not tech savvy.

It still hurts me even though I started with js

Javascript has automatic semicolon insertion, not foolproof.

@@TheNewton That's the code editor extension, JS totally works without the semi

Actually semicolons are fkng redundant trash. By using them you do the machines work. If you write all your code on one line you MAY write them so the code work but then you probably shouldn't write any code at all.

Look at Golang. Even Ken Thompson realized this deep truth ;)

Same here!

useless but ok

@@ricko13 color coding

@@ricko13 vbvlhbbvvbbvkbgvphvbbbb)))?:-::;::?--?-;;:::;::::-::;;::::?-?-::-:;::;:::?(-?0:?)-)-??);::(;;:--:-:;-;:;;::;-?::/;;:-;:;-:?:?-)!?;??;?)?))????-?:;-:-)-:-:);;--::-:!:;::::::::::(;--:;)--:!: Vmlbvbbvvmgggklgbgvvvvbhgvvgbnbbvvvvkvvvg Gggvkvvvvphglbgvlbmmmmmvlhvvlvkmjvvvbmbbvvgvvhkvvgvhvgbggbbvvbvbbgvvvmvvklmmkvkggbgvgvvgvvbpvvgvghvvv Bvmvgjvggkggvhhh Bbvbvvvvb CclvnmgvgvvvpvvgvgggmvvvvbggvvvgpmkgvvbkkvbmmllmnblkglhbbvkvvvvvmgggvvvvvgbvngvvbgvvvbxvmvmkmbvvlvvbvvbvvvgvgbvgbvvbvvhvbvvvhgvvbvvpvgvbvgbvbbvvlfkkmmmmllkmmhbgvbhbbvmvbvgbgvvbvhggvvbbvvbbgvgvvmghmbvmbggmmHvlkklhmvhvjvvbbbbvvvgvmvbvhvggvvgvvpbvgpbvmvgvvmgmbmkvgkmmmmkmvvhbvvbcvvggvgvvvbvvvvvvbvbbgvcvvvvvvvvvvmvvbgvvbvmvblmlmhmkmmmvlmmkmmmlvvvgmgvhvvkvbvvbghvbvvvvmggvbvbvgvvvvbvvggvvvmpvvmvvhvvvgkmhlkbmmmmxpmkmclbgggg Gbvvvvvnbbgvbvvgbgvvvvvvvgvgvhkgvvmvpvpvbbmkbmmvvmmmlmlmmmmlvlhbvvhvbvkgvvvvbhvgppvvbvggpvbvbgbvmhggckvbvmvmvvvkgvpmvvgvvhkckkkvmmvkvmmkvvmvbvvvvvgbvnbgvvggvvhbbgvbvvvbhmlbbvbghvkvggpgvbvkgvpgbhbghbhmlgmlmmlvvvgvvvvbvhvvvvvvvvhvvgv bvbvvvvvpkvmgvmmlmvhhbvvhbbvVgbvvbvvvbbvvbbvbbbmhvgbvvvbbmhbpmlglkgmvvbvbbvvvgbbvbbvvbvvhvvmbvvhpvbbkg Gbmvhvhgkmmmmlklgvbvvlgvvbvbvvvvvvvvvvvvmpvgvvcbbnjkmkmkhbmmmmmbvkvvnmbvvvvvvggvggvvvvvppbbbcvhmmmmlkbbbbvbhbgvmvbmvvvhvbbvmvkbmmmmvbpvvlggvvvvvvvvbvgvm bvmvmvpbknkvmbmmmlmmmmccbvhvbbvvbmvb Bgvvpvvbpgvvpbbvv Hmv Mkbmvvglcmvpgvph Gvv Ggvbvvvvgmvvvvgvgvvvjvpvgpvgvvgvvvgmhg lkmvmlmvgvbvv bb bb bb bb bb bb bb v Vgbvggkvvvbvpv

ive seen it, if you load pixi js in your project you will see a cool box in your console

@@spartaboss8387 ??????

🤣

One of the best puns I've heard in a long time...

function names are written in lower case, not Upper Case. (unless it's an object constructor)

@@j0code Yes and how you write it is said by a table of stone. In germany we write names and things in upper case (which is in english by the way not written upper case itself). I know we are not the entire world but it is the natural behavior all around me. And surprise again: Func1 will work. It worked in Netscape Navigator, Mozilla Browser, Firefox and now in Chrome. We can make things complicated or use the time for the better good, shouldn't we?

It's not really a keyword. It's just a property of the function. The reason it's crossed out is because it's a global variable in the browser that's a property of the window object.

@@SealedKiller a keyword is a word crossed out because it is used. So why exactly is a property identifier not a keyword? 8-)

@@yksnidog Because it's a global variable that's used by the window object. When you assign something to the variable 'name' it assigns it to window.name. It's not a keyword, it's not reserved. It's just an identifier.

Maybe...

here same from Korea

Keydi, you need something, something you got the illusion you r getting with each video

Ese like what?

@@keydib8913 Yes, because you are girl and we are not gays =)

I use price = Number(price)

this also works :P price = '0.05' * 1. Because you can not multiply a string, JS now it must be integer

Nice catch. You have a sharp mind!

Yep. It's a nullish coalescing operator for methods

@Michał Kasprzak this is because until JS3/4 (I'm not sure of the version name) there was no difference between array and object. Array was only object with numeric index, and not a different type

CoffeeScript did this back in the day

@@noctislupo93 aren't they still very similar? you can still access an object attribute using brackets [], like it was an array of key => value, keys being string. I use that a lot to access object attribute dynamically through the use of a string function parameter

But that won't do a check I guess

Default assignment will only assign for undefined, not nulls

@@Champagnerushi I know. But he is not using null.

default assignments are "undefined"... And if you do set a default value yourself, VSCode will let you know what type is expected if you arent using typescript. so if you create something like function test ( arg = [] ) {}; VSCode will tell you that arg is expected to be an array.

Semicolons are trash

That's what I was thinking! His way is inefficient.

That's just the way he presented it, you can use it anywhere with any variable not just function parameters.

​@@can_pacis That's not what @vmalvoq meant. He meant why not just use default parameter values. function calculateCost( itemCost, taxRate = 0.05, itemName = 'unknown item' ) { const totalCost = itemCost * (1 + taxRate); console.log(itemName + ' costs $' + totalCost); } The main difference is that the default parameter value is only used if the parameter value is undefined. In my above example function, if the taxRate or itemName are null, the default value on the parameter will not be used. > calculateCost(100, 0.07, 'my item'); > my item costs $107 > > calculateCost(100, undefined, undefined); > unknown item costs $105 > > calculateCost(100, undefined, ''); > costs $105 > > calculateCost(100, null, null); > null costs $100

@@MatthewWeiler1984 I can't exactly remember what I was talking about and I just don't want to rewatch this video but it looks like you are right, I'm not sure. If so, thanks for correcting and have a good day

Or maybe don't.

​@AngryJoeIsRacist Super Racist Typescript is not an easier version of JavaScript. It's a superset of JavaScript, meaning all JavaScript is valid Typescript. I'd argue you shouldn't use Typescript until you have understood why you are using it and how vanilla JavaScript approaches the same issues. Because otherwise you're adding a lot of complexity and overhead for no reason.

​@AngryJoeIsRacist Super Racist You said - and stop me if I quote you incorrectly here - "you can make life harder on yourself" in response to my statement to "perhaps [not use Typescript]". Implying - and I will use simple deduction here, stop me if you have trouble following - that somehow there is an added cost to using Vanilla JS. I made arguments as to why that isn't the case. 1) JavaScript is easier. Which you just agreed on. So that's not the added cost. 2) JavaScript is valid TypeScript. A vast majority of issues you encounter in Vanilla JS you encounter in TypeScript. That's why it's relevant that TypeScript is a superset. (And comparing programming languages that literally contain the exact same vocabulary and grammar to spoken languages that do not is a false equivalent. But I'm guessing you know that.) So more issues in Vanilla JS is also not the added cost. 3) Typescript adds overhead and complexity, because it adds additional grammar (that's the complexity part) and requires you to use a lot of the additional grammar to get a use out of Typescript (that's the overhead part). That would mean Vanilla JS is both lower in complexity and lower in overhead. So that's not the added cost. Now that I have cleared that up for you, since apparently that was necessary, please, enlighten us as to why Typescript is supposed to "make life easier" instead of flailing at my comment line by line but provide no arguments of your own.

​@AngryJoeIsRacist Super Racist See, now you're actually making arguments. Thank you. That's all I wanted.

i miss linq

You mean “stolen from c#”. In next js edition: “this” is “this” and not some random sh**.

yup, default props,but it does not works for null or empty values

@@aashiqahmed5273 Which I'd argue is a good thing. Null shouldn't be treated as `undefined`. They are inherently different things and should often be treated as such. Passing null into places will show you that something is incorrect much faster than replacing it with a default value.

@@aashiqahmed5273 they are not props they are parameters

٠

Empty lol

No

@@reinieltredes8306 ok thanks for that detailed explanation

I'm a beginner. I tried your sample and... It works. Thanks dude

@@KalmeMarqTG tried on pure js. It works too

Transpile with babel

@@KinSlay1337 unfortunately it creates less readable and maintainable code for the person that might need to update something in the future :( So even if it technically works, it's not acceptable for maintainability.

@@Hearrok you can always keep the untranspiled code to be maintained but I guess people where you work are too set on old practices if it's not an option

@@KinSlay1337 It's not the people it's the system engine interpreters that can't handle higher versions. Also having two copies of the same code but in different versions would add even more complexity to everything. It's not that hard to just write code with older styles. It's just that it would be nice to have things like arrow functions x)

Or console.dir to extract info

Thank you!

I was about to say the same thing