JavaScript Fundamentals: A Complete Guide
JavaScript is the backbone of modern web development. Whether you’re building interactive websites, server-side applications with Node.js, or mobile apps, understanding JavaScript fundamentals is crucial.
Variables and Data Types
JavaScript supports several data types:
- Primitive types: string, number, boolean, null, undefined, symbol, bigint
- Reference types: objects, arrays, functions
// Variable declarations
let name = "Alex";
const age = 30;
var isActive = true;
// Modern destructuring
const { title, author } = book;
const [first, second] = array;
Functions and Scope
Functions are first-class citizens in JavaScript:
// Function declaration
function greet(name) {
return `Hello, ${name}!`;
}
// Arrow functions
const multiply = (a, b) => a * b;
// Higher-order functions
const numbers = [1, 2, 3, 4, 5];
const doubled = numbers.map(n => n * 2);
Asynchronous JavaScript
Modern JavaScript heavily relies on asynchronous programming:
// Promises
fetch('/api/data')
.then(response => response.json())
.then(data => console.log(data))
.catch(error => console.error(error));
// Async/await
async function fetchData() {
try {
const response = await fetch('/api/data');
const data = await response.json();
return data;
} catch (error) {
console.error('Error:', error);
}
}
Conclusion
These fundamentals form the foundation of JavaScript development. Practice these concepts regularly to build strong programming skills.