The Coder Bros — Master Modern Development

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Lessons

JavaScript Fundamentals

Slide 1 of 7

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Variables & Types

JavaScript Variables

Declaration:

let: Block-scoped, can be reassigned
const: Block-scoped, cannot be reassigned
var: Function-scoped (avoid)

Data Types:

string, number, boolean, null, undefined, object, symbol, bigint

javascript

let name = "Alice";
const age = 25;

// Dynamic typing
let value = "Hello";
console.log(typeof value);
value = 42;
console.log(typeof value);

// Template literals
const greeting = `Hello, ${name}! You are ${age}`;
console.log(greeting);

// Strict vs loose equality
console.log(5 == "5");  // true
console.log(5 === "5"); // false