All language subtitles for 5. Node.js Runtime

Welcome back.

So we just learned what note is kind of.

We're still working there, but the other piece of information that we need to solve is what is a JavaScript

runtime?

Because Node is a JavaScript runtime.

It's not a programming language, it's not a framework.

It's a runtime.

So let's demystify that.

What is a runtime?

Now this idea of a runtime, we're going to deep dive into it a little bit later in the course.

So I'm just going to skim the surface, but you can think of it as a JavaScript environment, an environment

that allows us to run JavaScript as well as do some extra stuff.

Now the way node works is that it has the V8 engine, which, as we learned, makes our JavaScript code

run really efficiently.

And every time the Google engineers upgrade the V8 engine, which is very often well know, it automatically

gets faster and faster with each improvement in the V8 engine.

So automatic performance boost just by that.

But in order for it to do a lot more than just write JavaScript, it might want to do different things.

Maybe read files, maybe access databases, maybe just run.

Some things that aren't part of the V8 engine aren't part of JavaScript.

And that's where this Lib U.V. comes in.

You see, no GS in a simplified form is simply a way for us to give a JavaScript file to the Node.js

runtime.

It's going to go through the V8 engine.

It's going to read the JavaScript.

And any time it sees something that maybe isn't part of JavaScript, it's going to communicate with

this Lib U.V. library with a cool dinosaur logo.

But what does it mean?

Well.

We can just simply Google Lib UAV.

Libya V is a multi-platform C library that provides support for asynchronous i o based on event loops.

Don't worry, we'll cover that later in the course.

It's essentially a library that allows us to do some really neat features with Node.js that make it

great for things like web servers, things that we're going to build throughout the course.

If we actually go to the Node.js GitHub repo, which anybody can access because it's open source and

we go into the source folder, you'll actually see that at the bottom.

We're going to access the red meat that says no eggs, C++ code base, and you can read about this if

you really want to dive deep.

But essentially, what Node and Brian Dahl did was combine the V8 engine and this Lib UAV, which is

written in C++ V8 engine is written with JavaScript and C++, and he created the bindings between them

so that they can communicate so that whenever they encounter something that maybe needs asynchronous

Io, well, then we hand it over to the Lib UAV.

Now I know this is kind of confusing, and we're going to dive deeper into this topic, but that's one

note it's a JavaScript runtime is an environment for us to run JavaScript that gives us a little bit

more than just the V8 engine.

Now, let me ask you another question.

Is a Web browser a JavaScript runtime?

Pause the video and think about it based on what you learned is JavaScript runtime.

Well, let's do a quick search here.

Is Web browser a JavaScript?

Runtime, well, good sentencing on my part.

All right, so we go to StackOverflow, looks like this person has the exact same question as us.

And if we go to the answer, we see a browser contains a JavaScript engine.

Hey, we know what that means.

And the engine implements a JavaScript runtime, which includes call stack heap and event loop.

Don't worry, we're going to learn about those soon.

The browser also usually includes a set of APIs that augment the JavaScript runtime and make asynchronous

blah blah blah blah blah blah blah, blah blah.

In a sense, yes, the web browser is a JavaScript runtime, right?

If we go to our console, we can actually run code that isn't part of JavaScript.

For example, console dialog isn't actually part of the JavaScript Spec. It's just something that the

browsers allow us to do things like alert.

Well, those are very Web specific, the browser implements this alert feature that we can use and all

of these.

Are part of what we call the window object in the browser, the window object is a set of tools that

the browsers give us that we can use that aren't part of JavaScript, but allow us to have multiple

functionalities.

So it's a JavaScript runtime.

Remember the V8 engine combined with some extra functionality in the same sense with Node.js?

We have that functionality, except because it's not a browser énergies.

If you do window, you're going to get an error in Node.js.

We have something called global instead of the window.

But if I do it here, I get an error because the browser doesn't know about global.

Don't worry, we're going to dive into this specific thing in the next video.

But before I keep talking and keep talking, I want to go back to what we've learned.

Up until now.

How do you run JavaScript?

Well, you need a runtime.

You need some sort of an JavaScript engine and a runtime to be able to run the code, and that's what

no does.

So how do you run JavaScript outside of the browser?

You need to download a set of features so that your computer understands what JavaScript is, why you

want to do.

Node is, in a way, just a set of tools for us to write our applications.

That application uses the V8 engine to read the JavaScript, and any time there's something that requires

some sort of things like work or threats, event queues, event loops, again, something we'll cover

later on.

Well, we use the Lib EUV Library and Ryan Doll created these bindings for us that communicates between

V8 and Lib U.V..

So then now we're able to write JavaScript gets read by the V8 engine and then gets sent back to Libya.

But we don't have to worry about what's underneath the hood.

We can just run JavaScript code.

And by the way.

This is exactly how it works with other programming languages as well.

For example, if you wanted to run Python, my computer doesn't know what Python is.

Yes, maybe it might be pre-installed on my computer when I bought it.

But most likely, if I write Python and throw it to the computer, the computer is going to say, Who

are you?

I don't even know what that means.

So just like we will in the next couple of videos, we need to actually install Node.js so that we can

download these tools to run JavaScript outside of the browser in the same way.

If I wanted to, let's say code in Python, I'd have to go to the Python Dawg website and then download

Python.

Or the Python, what we call interpreter, so that my computer can read Python code.

Now let's take a break here.

I know we're covering a lot.

Your brain might be a mush right now.

But don't worry, everything's going to fall into place.

Bit by bit.

For now.

Grab a cup of coffee and I'll see you in the next one.