007-data-type.js

// 1. What are Data Types?
// const age = 25; // This is a number
// const name = "JS"

// 2. Number Data Type
// const age = 25;
// const price = 35.99;
// const temp = -10;

// const sum = 10 + 5; // 15
// const product = 10 * 5; // 50

// Numeric values:
// const infinity = Infinity; // Represents infinity
// const notANumber = NaN;

// const result = "Hello" / 2; // NaN

// 3. String Data Type
// const firstName = "Java"
// const lastName = "Script"
// const fullName = `Java Script` // Backticks (template literals)

// const greeting = `Hello, ${fullName}!` // Hello, Java Script

// console.log(greeting);

// const firstName = "Java"
// const lastName = "Script"
// const fullName = firstName + "" + lastName

// console.log(fullName)

// 4. Boolean Data Type
// let isLoggedIn = true;
// let hasPermission = false;

// let age = 18;
// let isAdult = age >= 18; // true

// if (isLoggedIn) {
//   console.log("Welcome back!");
// } else {
//   console.log("Please log in.");
// }

// 5. Null Data Type
// let user = null; // Explicitly no value

// user = "My Name"

// console.log(typeof null)

// 6 Undefind Data Type
// let userName;
// let person = {name: "Jhon"}
// console.log(person.age)

// 7. Checking Data Types
// let age = 25;
// console.log(typeof age); // "number"

// let name = "John";
// console.log(typeof name); // "string"

// let isActive = true;
// console.log(typeof isActive); // "boolean"

// let user = null;
// console.log(typeof user); // "object" (the bug we mentioned)

// let email;
// console.log(typeof email); // "undefined"