JavaScript · Quick Reference

Lesson 4 — Operators Cheat Sheet

JavaScript

In one line: Arithmetic operators perform mathematical calculations. JavaScript supports all the standard math operators plus the powerful exponentiation (**) operator introduced in ES2016.

Key Ideas

1Arithmetic Operators. Arithmetic operators perform mathematical calculations. JavaScript supports all the standard math operators plus the powerful exponentiation (**) operator introduced i...

2Assignment Operators. Assignment operators combine a mathematical operation with assignment into a single shorthand. They make code shorter and more readable.

3Comparison Operators. Comparison operators compare two values and return a boolean (true or false). The most important distinction in JavaScript is between loose equality (==) and strict eq...

4Logical Operators. Logical operators combine boolean expressions. They also support short-circuit evaluation — a powerful pattern used everywhere in real JS code.

5Ternary Operator. The ternary operator is a one-line if/else expression. Syntax: condition ? valueIfTrue : valueIfFalse. It's perfect for simple conditional assignments and JSX in React.

Code Examples

let a = 10, b = 3;

console.log(a + b);   // 13 — Addition
console.log(a - b);   // 7  — Subtraction
console.log(a * b);   // 30 — Multiplication
console.log(a / b);   // 3.333... — Division
console.log(a % b);   // 1  — Modulus (remainder)
console.log(a **...

let score = 100;

score += 10;  // score = score + 10  → 110
score -= 5;   // score = score - 5   → 105
score *= 2;   // score = score * 2   → 210
score /= 3;   // score = score / 3   → 70
score %= 8;   // score = score % 8   → 6
score **= 2; // score = sco...

let x = 5, y = 10;

console.log(x == 5);    // true  — loose equality (type coercion!)
console.log(x === 5);   // true  — strict equality (NO coercion)
console.log(x != 10);   // true  — loose inequality
console.log(x !== y);   // true  — strict inequality
...