Day:1 JavaScript Basics: Data Types, Variables, and Functions

JavaScript is one of the most widely used languages for web development. In this post, we'll cover the essential building blocks of JavaScript: data types, variables, and functions.

Data Types in JavaScript

JavaScript has several built-in data types. These are categorized into primitive and non-primitive (object) types.

Primitive Data Types

String – Text data

let name = "Alice";

Number – Integer or floating-point numbers

let age = 25;

Boolean – true or false

let isStudent = true;

Undefined – A variable that has been declared but not assigned a value

let x;

Null – Represents an intentional absence of value

let data = null;

Symbol – Unique and immutable primitive value

BigInt – For large integers

Non-Primitive (Objects, Arrays, Functions)

let person = { name: "Bob", age: 30 };
let numbers = [1, 2, 3];

Variables: var, let, and cons

*JavaScript uses keywords to declare variables:
*
var – Function-scoped (older way)

let – Block-scoped, can be reassigned

const – Block-scoped, cannot be reassigned

let city = "New York";
const country = "USA";

Functions in JavaScript

Functions are reusable blocks of code that perform specific tasks

Declaring a Function

function greet() {
console.log("Hello, world!");
}

Calling a Function

greet(); // Output: Hello, world!

Function Arguments

You can pass values to functions using arguments.

function greetUser(name) {
console.log("Hello, " + name + "!");
}

greetUser("Alice"); // Output: Hello, Alice!

Return Values

Functions can return values using the return keyword.

function add(a, b) {
return a + b;
}

let sum = add(5, 10);
console.log(sum); // Output: 15