JavaScript Operators: The Basics You Need to Know

Operator is a tools They let you do math , compare values and make decisions .

What Are Operators?

Operators a symbol that perform action on values

// Operator: +
5 + 3 = 8

// Operator: >
10 > 5 = true

// Operator: &&
true && false = false

Different type of operator exist in JavaScript .

1️⃣ Arithmetic Operators (Mathematical operator)

Arithmetic operators let you do basic math.

Simple Addition

let a = 10;
let b = 5;

let sum = a + b;
console.log(sum); // Output: 15

All Arithmetic Operators

let num1 = 20;
let num2 = 4;

console.log(num1 + num2); // Output: 24 (Addition)
console.log(num1 - num2); // Output: 16 (Subtraction)
console.log(num1 * num2); // Output: 80 (Multiplication)
console.log(num1 / num2); // Output: 5  (Division)
console.log(num1 % num2); // Output: 0  (Remainder)

What is Modulo (%)?

Modulo operator gives you the remainder after division

console.log(10 % 3); // Output: 1

console.log(15 % 5); // Output: 0

let number = 7;
if (number % 2 === 0) {
  console.log("Even");
} else {
  console.log("Odd"); // Output: "Odd"
}

2️⃣ Comparison Operators

Comparison operators check if something is true or false.

They always give you a result: true or false

The Operators:

Example 1: Simple Comparison

let age = 18;

console.log(age > 10); // Output: true
console.log(age < 20); // Output: true
console.log(age === 18); // Output: true

Example 2: Greater Than and Less Than

console.log(10 > 5); // Output: true
console.log(3 > 8); // Output: false
console.log(5 < 10); // Output: true
console.log(8 < 3); // Output: false

⭐ IMPORTANT: == vs ===

== (Double Equal) - Loose Comparison

console.log(5 == "5"); // Output: true
console.log(0 == false); // Output: true
console.log(1 == true); // Output: true

=== (Triple Equal) - Strict Comparison

console.log(5 === "5"); // Output: false
console.log(0 === false); // Output: false
console.log(1 === true); // Output: false

Visual Explanation:

3️⃣ Logical Operators (AND, OR, NOT)

Logical operators help you to check condition they are true or false.

The Operators:

AND Operator (&&)

Both conditions must be TRUE

let age = 20;
let hasLicense = true;
let hasPhdDegree = false;

if (age >= 18 && hasLicense === true) {
  console.log("You can drive!"); // Output: "You can drive!"
}

if(age >= 18 && hasPhdDegree === true) {
  console.log("You become a doctor!"); // Output: "You become a doctor!"
}

Truth Table for AND (&&):

true  && true   = true   ✅
true  && false  = false  ❌
false && true   = false  ❌
false && false  = false  ❌

OR Operator (||)

At least ONE condition must be TRUE

let hasDebit = true;
let hasCredit = false;

// Can buy if you have debit OR credit card
if (hasDebit || hasCredit) {
  console.log("You can pay!");  // Output: "You can pay!"
}

Truth Table for OR (||):

true  || true   = true   ✅
true  || false  = true   ✅
false || true   = true   ✅
false || false  = false  ❌

OR Operator (||)

At least ONE condition must be TRUE

let hasDebit = true;
let hasCredit = false;

// Can buy if you have debit OR credit card
if (hasDebit || hasCredit) {
  console.log("You can pay!");  // Output: "You can pay!"
}

Truth Table for OR (||):

true  || true   = true   ✅
true  || false  = true   ✅
false || true   = true   ✅
false || false  = false  ❌

NOT Operator (!)

Reverses true to false, and false to true

let isSunny = true;

if (!isSunny) {
  console.log("Take an umbrella");
} else {
  console.log("Enjoy the sun!"); // Output: "Enjoy the sun!"
}

Truth Table for NOT (!):

!true  = false
!false = true