What's New
In JavaScript?


wesbos.com@wesbos

I'm
Wes Bos


These slides will be available shortly after this talk
I'll tweet the link out.

@wesbos

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JavaScript is Always Evolving

ES6

ES2016 (ES7)

ES2017 (ES8)

New DOM Apis

This Talk

Reaaaady?

Let's go!

Promises

Not brand new, but let's do a quick review

Promises are an IOU for something that will happen in the future

All of these things take time, we simply kick off the process and move along with our lives.

But why do we do it this way?

JavaScript Waits for no one!

Almost Everything Is Asynchronous

Let's say we wanted to do a few things:

Do you need to finish making coffee before you can Start Breakfast?

Would it make sense to wait until coffee is made and consumed before we even start cooking breakfast?

No - we want to start one thing, come back to it once it's finished, and deal with the result accordingly!

Most new browser APIs are built on Promises, or Observables

More on Observables in a bit

fetch()

Axios

Many, many more

PaymentRequest, getUserMedia(), Web Animation API

It's easy to make your own too!

Christmas Tree Callback Hell

we get it
Promises are great.

buuuuuuttt

What's the deal with .then()?

It's still kinda callback-y

Any code that needs to come after the promise still needs to be in the final .then() callback :\

Async + Await

Async + Await still is promises, but with a really nice syntax

Let's break it down

JavaScript is almost entirely asynchronous / non-blocking

great! - But it's hard to read/write

PHP

JS

😕😕😕

The PHP is easier to read

The JS is more performant

I'm not really happy

Synchronous looking code, without the wait.

How does it work?

1. Mark it as Async

2. await inside your async fn

Best of Both Worlds!

Another Example

Slow...

Why wait for Wes?

Remember, async+await is just promises

Error Handling

A few options (which we don't have time for)...

Done with Async+ Await!

Let's see more new stuff!

Intersection Observer

How do you know when an element is on screen?

With Intersection Observer, you can be alerted when an element is fully or partially scrolled into or out of view.

Uses

Google Developers

Ready for Meta?

How does it work?!

1. Setup some Options

2. Create an empty Observer

3. Give it a callback

4. Observe Away!

Payment Request API

Every single online store needs to reinvent the checkout form.

We're all just trying to do the same thing - collect payment info from the user.

The Payment Request is a standardized browser API to collect billing and shipping information from your users.

[Google Developers]

So, Does the Browser Charge Your Card?

nope!

Is it secure?

The same, or more!

getUserMedia()

Not new at all

BUT

Safari Doesn't give a shit

September 2017 / iOS11

playsinline and getUserMedia()

Promise Based!

Resize Observer

per-element resize events!

Gateway Drug to Element Queries!

WOWOWOWOWOW!

Some cool stuff!

What About Support?

Async + Await via Babel

Resize Observer Polyfillable, but expensive.

Intersection Observer has an official W3 polyfill

Web Payment is easily polyfillable

or Fallback to checkout form

getUserMedia is everywhere

text

(504) 229-6828

#newjs 5 Best talk!

— or — #newjs 1 garbage fire

Thanks
Folks!

@wesbosWesBos.com