Name: JS IIの未来への回帰：予見できることを超えて｜William Martins｜JSConf Korea 2019 (Back to the future of JS II: Beyond what we can foresee | William Martins | JSConf Korea 2019)
Uploaded: 2021-01-14T10:23:01.000Z
Duration: 24 min 56 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

So you will not talk about Mr Hunter seeing racy games or football.

Um, before I start my presentation, just a small disclaimer.

Um, all the proposal one on show here are under construction.

Ah, The main tincture in here is to give you a sneak peek about the future of JavaScript and try to help you to understand the use case and the pros and cons and off all of these teachers and show.

Amazing work that the sitter ninth community's doing to improve the language we love.

Um, some of some of this future mayor might not be present on javascript.

If I have some concern off, you wanna express your, um, your support with some of these proposals, please use this link below an open issue or put the star and getting getting engaged.

So the agenda for today we're talking about a parent matching pipeline operator buying their A C T and give some opinions.

So whenever you see a rat border and the light is just my opinion, if you disagree, just dinner or talk to me afterwards.

That said so, uh, to give her back with background motivation off the first picture, I won't talk about a bit more about a conditional in jail escapes.

Nowadays, we have only three ways to do conditions.

Drivers in JavaScript We need to weigh, have f l statement, sweet statement and try and turn on the expression, uh, just to set up a common ground to everyone.

Um, an expression is something that evaluates down to a value and in statements.

So NFL statement requires a condition which evaluates to true fear.

Um, if the conditions true, it execute the adjustment block, and if it's not, it tries to execute decibel Elsa book if you have one, but it can get complicated.

This of simple function that just tries to, um, return emoji that tries to reflect the team.

The current temperature, Um, as you can see here dysfunction.

It's just ah, if statement that if it's true, just returned the emoji, But Elsa's statement its again.

So this is a way to concoct innate and chain one.

If statement off the daughter, um, it can get you can get really freaky because I'm not even talk about, uh, nest.

Right, Um, for this kind of special special checks, when they have a lot off small ah, a lot of options and the smoke all to react to, I think sweet statesman's a handy too.

So let's check how sweet statement works.

Whenever you have, you need to, um, react toe cup off choice or you have a lot off, um, a lot of chunk off Goto executes.

But when you have a multiple choices and the Justice Mao was more set of comments, I think sweet statement could be a good choice.

The sweet statement works as the falling given, um, next expression inside the princes and switch.

This case is statement, and when he matched with the 1st 1 Egypt That's the start important point of these, uh, um, block statement.

And then that's why we have the break statement.

There are two things I want to highlight here.

Ah, using a break statement, because just by using a return, I have, ah, my function stopping and at that at that line.

And the second thing is, people may not get it, but the case statement accessorize expressions well, so we can put instead of just a constant that this is the most used, uh, used use case there.

You just put a constant and you put this expression that switch.

So then I stopped, like a used X on the constant and switch, and they used the expression there.

So the tornado potato become popular recently because, uh, for the functional developer fen Andi, who tried to write the code with as much expressions possible, it basically works.

If this if this condition is true, it runs the 1st 1st book after the question mark.

It runs what we have after Colin and since turning expression eternity is the expression we can write that function using our function and that tries to make everything more Quincy's.

But then you have a cold like this and I don't know.

You feel like you're under like, but there are a lot of people that, like this kind of coat, I'm not heated yet.

And as you can see, we have three ways to the conditions nowadays in Javascript.

Could you imagine what would happen if you mix if statement with sweet statement and the power off destruction?

Ah, just structuring, veteran, very matching to understand how pregnant match works.

Um, I need to use a toy example to be able to explore.

So, um, let's suppose I have a list of shapes and I need to look in.

Detect all the circles Red scare square and big blow triggers.

How could they do this nowadays with if statement, um, just to give, um ah, small context.

Um, this is the simple entry, and this is one of potential a solution for the problem.

It's tricky because it can grow as the requirements grows.

You can keep put if in there as more the more you have for their requirements.

Because of the time here, I would just explain the car concepts.

And if you were interested in it, you can either check the documentation on the get her every poster or talk to me afterwards.

Um, this is the case statement which defines the start of the pattern matching, um block.

Then we have the the winkles, which is divine.

Then today again, you can have more in the speck in Ah, repose story.

Okay, um, in this first winkles, we are We have a splitting to like the first part before the error is the match pattern.

And the second part is the wing closed body.

So the match burner better re execute the body whenever the shape of the pattern match the shape.

Perfect expression in this case, every single object that has the type of circle.

Um And then, to achieve the second you use case, I can just create another pattern which is type square color red.

You see, if statement in the middle is this cold match word, it means that even though the match match with the object, if the if statement which is called magic work returns false, it will not executed the block and less cases.

JS IIの未来への回帰：予見できることを超えて｜William Martins｜JSConf Korea 2019 (Back to the future of JS II: Beyond what we can foresee | William Martins | JSConf Korea 2019)