JavaScript Basics Cheatsheet

📦 Variables

Variables store data. Think of them as labeled jars. Use let, const, and var to declare.

let name = "Naveen";
const age = 25;
var mood = "excited";
    

Fun Fact: const means you can't reassign the value later.

🧮 Operators

Operators are symbols that perform operations on values:

• Arithmetic: +, -, *, /, %
• Assignment: =, +=, -=
• Comparison: ==, ===, !=, >, <=
• Logical: &&, ||, !

let sum = 10 + 5;       // 15
let isAdult = age >= 18; // true
let canVote = isCitizen && isAdult;
    

📏 Data Types

JavaScript has dynamic types:

• String: "Hello"
• Number: 42
• Boolean: true/false
• Undefined: not assigned
• Null: intentionally empty
• Object, Array, Function

let score = 99;
let passed = true;
let student = { name: "Naveen", age: 20 };
let hobbies = ["coding", "gaming"];
    

🧰 Arrays & Objects

Arrays store lists. Objects store key-value pairs.

const fruits = ["apple", "banana", "mango"];
console.log(fruits[1]); // banana

const user = {
  username: "naveen",
  points: 120,
};
console.log(user.username);