Case Sensitivity

JavaScript is case-sensitive. myVar and MyVar are different identifiers.

JavaScript Statements

JavaScript statement is terminated with a semicolon(;)

Each instruction is a statement. Use semicolons (;) to separate them.

let x = 5;
let y = 10;
console.log(x + y);

JavaScript Comments

// Single-line comment

/* Multi-line
 comment */

JavaScript Variables

Declared using var, let, or const.

let name = "Alice";
const pi = 3.14;
var age = 25;

JavaScript Identifiers

• Must start with a letter, underscore (_), or dollar sign ($).
• Cannot start with a number.
• Examples: userName, _count, $price

JavaScript Data Types

• Number: 10, 3.14
• String: "Hello", 'World'
• Boolean: true, false
• Null: null
• Undefined: undefined
• Objects & Arrays: {}, []

Operators

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

JavaScript Functions

function greet(name) {
 return "Hello " + name;
}

const add = (a, b) => a + b;

JavaScript Blocks

Use { } to define block scope.

if (true) {
 let x = 5;
 console.log(x);
}

Whitespace

JavaScript ignores extra spaces, tabs, and line breaks. Use them only for readability.