Learn to build web applications using Node.js and the Express framework.

Become a MEAN Stack Developer

Node.js is a runtime environment that enables JavaScript to run outside the browser. In this module, we'll learn the fundamentals of Node.js to build portable applications. We'll learn about the components of Node.js and make patterns using these. We'll also explore the API to learn how to create modules and write code for unique data files. Moreover, we'll delve into the features and practices of JavaScript and build a REST API using the Express framework from scratch. Moving on, we'll use Passport.js and JSON web tokens to establish authentication tokens. We’ll then create a live trivia game with Socket.IO. By the end of this module, we'll be equipped with extensive knowledge to build rich and comprehensive Node.js applications running on the server with JavaScript.

Learn Node.js from Scratch

`SyntaxError: Assignment to constant variable.`

`TypeError: Assignment to constant variable.`

What will be the output of the following code?

```js
const name = "Robert";
name = "Robbie";
console.log(name);
```

What will be the output of the following code?
<pre><code class="language-js">const name = &quot;Robert&quot;;
name = &quot;Robbie&quot;;
console.log(name);
</code></pre>

**(True or False)** The `var` variables can’t be updated and redeclared within their scope. The `let` variables can be updated but not redeclared within their scope.

(True or False) The <code>var</code> variables can’t be updated and redeclared within their scope. The <code>let</code> variables can be updated but not redeclared within their scope.

What will be the output of the following code?

```js
let { a, b, ...pairs } = { a: 10, b: 20, c: 30, d: 40 };
console.log(pairs);
```

What will be the output of the following code?
<pre><code class="language-js">let { a, b, ...pairs } = { a: 10, b: 20, c: 30, d: 40 };
console.log(pairs);
</code></pre>

**(True or False)** The arrow function syntax below is valid, and when called, the function will return the output of multiplying `a` and `b`:

```js
const multiply = a, b => a * b;
```

(True or False) The arrow function syntax below is valid, and when called, the function will return the output of multiplying <code>a</code> and <code>b</code>:
<pre><code class="language-js">const multiply = a, b =&gt; a * b;
</code></pre>

A function that is nested inside of another function and has access to variables declared in its local scope and in the outer function’s scope but not in the global scope

A function that provides access to variables declared in its local scope to other functions

A function that is nested inside another function and has access to variables declared in its local scope, the outer function’s scope, and the global scope

What is the correct definition of a closure?

What is the correct definition of a closure?

Check your understanding of what you've learned in this chapter by taking this quiz.

Node.js Overview

The Node.js API

JavaScript Essentials Review

Building a RESTful API with Express

Authentication with Passport.js and JSON Web Tokens

Build a Live Trivia Game with Socket.IO

Appendix

Conclusion

Quiz Yourself on JavaScript Essentials