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Hello, welcome back to another latest feature of ECMAScript, they keep adding new things, but this

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is a really, really good one.

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So the latest one is 20/20, has some really neat features.

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And I want to show you some of my favorite ones.

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You can see them right here.

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Now, in this video, I'm going to talk about the street over here and then later on we'll have separate

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lectures for years, 20, 20 promise all settled and also global this.

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So those lectures will be titled East 2020 with the respective names, because these last two are better

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understood once we go over a few different new topics.

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So let's just focus on these three for now.

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Let's get started with Big End.

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And Big End is a really, really exciting new feature.

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It's a new type in JavaScript.

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What do I mean by that?

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Well, now in JavaScript we have.

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A type of.

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Big int.

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That's a new type, just like we have no, just like we have Bolian, we have different types in JavaScript.

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Well, let's test out that theory.

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Let's say we want to find out in our console over here.

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If I do, type of it gives me the type of something, so if I do type of four, it's a number.

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If I do type of let's say true, it's a boolean.

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But what if I do a type of a really, really large number?

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Well, that's still no, you see Big Int stands for Big Integer, but Andre, you just told me that

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Big Ant is a new type and how come I don't see it here?

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Well, to get the biggest type, let's clear this.

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You simply add the letter and after a number, so, for example, I can do one, and so if I do type

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of one RN, I get big ENT, but what does that really mean?

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Here's a fun little JavaScript trick or a gotcha.

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JavaScript has something called Max Safe Integer, and I'm going to link to some resources in this video

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that if you want to dive deep, you can read about.

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You see, JavaScript has something called a safe number.

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And it can go up to a certain Insaaf integer, which is this number right here, but as soon as you

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go a little bit higher, the calculations start breaking down.

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So if we scroll all the way down here.

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We find out that the Mac's safe integer has a value of this number.

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The reason behind that number is that JavaScript uses double precision floating point format numbers.

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That's a mouthful.

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Essentially, there's a limit to how much information we can store in memory, what kind of and because

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of the way JavaScript is built.

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And this is actually common with other programming languages as well.

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There's only a certain number that it can hold and big int solves this problem.

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So let's experiment here, because I always love when learning a new thing to experiment and make sure

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that we truly understand this.

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So I'm going to open up the console once again.

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And I'm going to try something, I'm going to say no dot max safe integer, which gives me the number

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that we have here.

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So this is the max that we can do in JavaScript.

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So what if I do this number?

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Plus one, does that work?

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Yep, it works.

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What if I do this number plus 10?

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Does that work?

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No, it doesn't, does it?

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This number plus 10 shouldn't equal that, you see how we just broke something?

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What if I do this?

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What if I do this?

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No, right over here.

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Minus one.

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Oh, boy, it's messed up again.

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Again, that doesn't make sense, does it?

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So big int is used when we want to use a number that's larger than this max safe integer and we want

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to do some calculations with it.

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So instead, if I do this.

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N minus one n.

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Well, I get an operation between these two big events and you see here that it's working, it's minus

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one.

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Again, if we try and do our Max Integer over here and we do plus 10, we see that this doesn't work

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as soon as we add NP to both of these.

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There you go.

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Our operations work.

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So we're able to use Big Ent. as a new type.

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Remember, if I clear this and I do.

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Let's say one end plus two and, well, I get a big into a type of big event that we can do calculations

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on, especially for big numbers.

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But as you can see, we can also just do regular numbers as well as long as we enter.

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And pretty, pretty cool most of the time.

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You're not going to use this feature.

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But it's nice to know and it's interesting to know that there are these limitations with JavaScript

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and big and solves them.

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All right.

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Let's learn something even more fun.

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Next one is nowish coalescing operator, actually, you know what, let's start with this one first,

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the optional chaining operator and then we'll go into the nowish coalescing operator.

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So let's pretend that we're playing Pokemon.

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Hopefully everybody knows Pokemon greatest game as I was growing up.

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I think it's still popular, though.

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All right, getting sidetracked, let's focus here, let's imagine that we have a user and we'll say

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Will Will is a Pokemon trainer and this user.

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Has, let's say, the Pokemon, Pikachu and Pikachu.

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Is, let's say, a species that is a mouse Pokémon.

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It's got a height.

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Of zero point four and let's say a wait.

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Of six pounds, so height zero point four centimeters and six kilograms of weight.

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Now, let's imagine that we want to find out the weight of Pikachu and hold it in a variable.

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While we would usually do is say let.

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Wait, and we'll say within here, we'll do Will Pokémon dot, Pikachu dot, wait.

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So if we cancel, let's make this a little bit bigger.

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And we'll do wait here.

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Let's copy this.

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Oh, man, we forgot to come over here, so let's try that again, let's copy this.

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And we get wait of six, just to be clear here, I can just say.

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All right, so this is working, but here's a problem.

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Let's say we have a different user and this time the new user, his name is Andre and Andre doesn't

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have Pikachu instead Andre has right you.

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Again, a different kind of Pokemon.

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It's still a mouse Pokemon, but some of the details are different.

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Say the height is zero point eight and the weight is 30 kilograms.

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So now, if I wanted to find out.

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The weight.

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Let's say, right, you.

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And I run this command.

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So let's say now instead of.

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Right, you listeners do wait to hear, and this time from Andre's Pokemon, we'll do this if I run

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this.

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I get an error, cannot read property weight of undefined and why is that?

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Well, because Andre doesn't have Pikachu, right?

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We don't have that Pokemon instead.

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We have.

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Right.

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You so when we tried to grab the Pikachu from the Andre Pokémon object, it's going to say, er.