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As you can probably tell by now,

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JavaScript is an extremely important programming language

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as a web developer

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because we can use it both in the browser,

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so on the frontend, as well as on the backend

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when we write server-side code with Node,

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and possibly with Express as a third-party library

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as we did it in the previous sections.

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Therefore, since JavaScript is that important,

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in this course section,

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we are going to dive deeper into it.

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And I explicitly wanna emphasize

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that we are diving into advanced JavaScript in general.

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What you'll learn in this course section applies

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to both the browser side, so frontend JavaScript

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if you use JavaScript in the browser,

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as well as backend server-side JavaScript with NodeJS.

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And I mean, in general, up to this point,

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the vast majority of things you saw applied

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to both sides; the key certain tags,

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and the core features apply to both sides.

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It's only specific functionalities,

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like requiring our files as we did it

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in the previous sections, requiring packages,

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working with something like the file system;

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these are things which are exclusive to NodeJS.

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But working with constants, with functions,

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loops, if statements;

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that is all general JavaScript code.

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And in this course section as mentioned,

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we are going to dive deeper into general JavaScript code.

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Now for that, in this course section,

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we are going to take a closer look at Functions again,

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and learn about some new features,

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and concepts are related to functions.

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And we will also take another look at Objects

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and Arrays and learn a couple of new things

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about those concepts.

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We are also going to take a look

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behind the scenes of JavaScript,

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and take a look at Reference and Primitive Values,

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and learn what exactly that is, and why it matters,

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and why you should understand it.

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And last but not least, we are also going to explore

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a concept called Asynchronous Code:

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Something we haven't really used up to this point,

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but something we will often need,

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especially when writing NodeJS code,

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but also in certain scenarios on the frontend

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which we'll explore later in the course.

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In this course section,

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I'm going to introduce you to Asynchronous Code,

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show you what that is, and how we can write

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such asynchronous code with JavaScript.

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Now, there's one important thing about this module

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which I wanna get out of the way right away:

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This course section will be challenging.

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There are many advanced concepts in here,

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which I will explain as simple examples,

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but because the examples are simple,

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it will not always be easy to see why that concept exists.

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Because of those simple examples,

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we don't really face any problems that would be solved

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by these more complex concepts.

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Now, we'll see the more problematic cases

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later in the course.

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But in order to then tackle them appropriately,

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I already wanna introduce these more advanced concepts

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here since later course sections will

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mainly focus on other tasks.

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But therefore, don't feel overwhelmed

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if some concept or the reason for the existence

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of some concept is not immediately clear

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in this course section.

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We'll see all the concepts taught in this section

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over and over again in later course sections again.

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And therefore, this course section here

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also acts kind of like a reference

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for a later course sections.

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And you can come back to this course module

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if some concepts taught in this module should still be

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unclear at a later point in the course.

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Attached to the last lecture of this course section,

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you also find a written summary, a cheat sheet

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which you can also use to look up certain concepts

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at a later point of time or to also have

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a written version in case the videos are not enough.

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Now for all of that,

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I'm in a brand new empty project,

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and we will write some JavaScript code here,

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which we execute with Node,

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but we will not build a complete Node web server;

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instead, we'll just leverage the fact

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that we can use the Node command to execute

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JavaScript files since that saves us the hassle

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of adding an extra HTML file,

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which we then have to open and evaluate

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in the browser all the time.

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Nonetheless, as emphasized everything

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I show you here applies to both the browser side,

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as well as the backend.