Node.js JavaScript Requirements
Quick Start
If you're new to JavaScript, don't worry!
Here are the key concepts you need to know before diving into Node.js.
We'll cover the essentials with simple examples.
Try It Yourself
You can run these examples directly in your browser's console or in a .js file using Node.js.
JavaScript Fundamentals
Before starting with Node.js, you should be familiar with these JavaScript concepts:
- Variables
- Functions
- Objects
- Arrays
- Asynchronous programming (callbacks, promises, async/await)
- ES6+ features
This page will give short examples of essential JavaScript concepts needed for Node.js development.
For a greater understanding for JavaScipt, visit our JavaScript Tutorial.
Variables and FunctionsGet your own Node.js Server
// Variables (let, const, var)
let name = 'Node.js';
const version = 20;
// Function declaration
function greet(user) {
return `Hello, ${user}!`; // Template literal (ES6)
}
// Arrow function (ES6+)
const add = (a, b) => a + b;
console.log(greet('Developer')); // Hello, Developer!
console.log(add(5, 3)); // 8
Try it Yourself »
Objects and Arrays
// Object
const user = {
name: 'Alice',
age: 25,
greet() {
console.log(`Hi, I'm ${this.name}`);
}
};
// Array
const colors = ['red', 'green', 'blue'];
// Array methods (ES6+)
colors.forEach(color => console.log(color));
const lengths = colors.map(color => color.length);
Try it Yourself »
Asynchronous JavaScript
// 1. Callbacks (traditional)
function fetchData(callback) {
setTimeout(() => {
callback('Data received!');
}, 1000);
}
// 2. Promises (ES6+)
const fetchDataPromise = () => {
return new Promise((resolve) => {
setTimeout(() => resolve('Promise resolved!'), 1000);
});
};
// 3. Async/Await (ES8+)
async function getData() {
const result = await fetchDataPromise();
console.log(result);
}
getData(); // Call the async function
Run Example »
Destructuring & Template Literals (ES6+)
const { name } = user;
console.log(`Hello, ${name}!`);
Key JavaScript Concepts
- Variables:
let(mutable),const(immutable),var(legacy) - Functions: Regular, arrow functions, and methods
- Objects & Arrays: Data structures for organizing data
- Modules:
require()(CommonJS) andimport/export(ES6) - Error Handling:
try/catchblocks
Quick Reference Table
| Feature | Node.js Support |
|---|---|
| let / const | Yes (since Node 6+) |
| Arrow Functions | Yes (since Node 4+) |
| Destructuring | Yes (since Node 6+) |
| Template Literals | Yes (since Node 4+) |
| Promises | Yes (since Node 0.12+) |
| Async/Await | Yes (since Node 7.6+) |
Exercise?What is this?
Test your skills by answering a few questions about the topics of this page
Complete the async function:
async function fetchData() {
return await .resolve('Hello!');
}
return await .resolve('Hello!');
}
Promise
setTimeout
console
