JavaScript Operators

1. What are Operators?

Operators are special symbols used to perform operations on operands (values and variables). For example, in 10 + 5, the + is the operator and 10 and 5 are operands.

2. Arithmetic Operators

Arithmetic operators perform mathematical calculations like addition, subtraction, multiplication, etc.

• + (Addition)
• - (Subtraction)
• * (Multiplication)
• / (Division)
• % (Modulus - Remainder)
• ** (Exponentiation)
• ++ (Increment)
• -- (Decrement)

Example

let a = 10;
let b = 3;

console.log("Addition: " + (a + b));       // 13
console.log("Subtraction: " + (a - b));    // 7
console.log("Multiplication: " + (a * b)); // 30
console.log("Division: " + (a / b));       // 3.333...
console.log("Modulus: " + (a % b));        // 1
console.log("Exponentiation: " + (a ** b));// 1000

Increment & Decrement

Prefix (++x): Increments the value, then returns it.
Postfix (x++): Returns the value, then increments it.

let x = 5;
console.log(x++); // 5 (Returns original value, then increments)
console.log(x);   // 6

let y = 5;
console.log(++y); // 6 (Increments, then returns new value)
        

3. Assignment Operators

Assignment operators assign values to JavaScript variables. The most common one is =.

let x = 10; // Assignment

x += 5;  // Same as x = x + 5
console.log("x += 5 ->", x); // 15

x -= 2;  // Same as x = x - 2
console.log("x -= 2 ->", x); // 13

x *= 2;  // Same as x = x * 2
console.log("x *= 2 ->", x); // 26
        

4. Comparison Operators

Comparison operators are used in logical statements to determine equality or difference between variables or values.

• == Equal to (value only)
• === Equal value and equal type (Strict Equality)
• != Not equal
• !== Not equal value or not equal type
• > Greater than
• < Less than

let num = 5;
let str = "5";

console.log(num == str);  // true (values match)
console.log(num === str); // false (types differ: number vs string)
console.log(num != 8);    // true
console.log(num > 2);     // true
        

5. Logical Operators

Logical operators are used to determine the logic between variables or values.

• && (AND): Returns true if both operands are true.
• || (OR): Returns true if one of the operands is true.
• ! (NOT): Reverses the boolean result.

let x = 6;
let y = 3;

console.log(x < 10 && y > 1); // true (both true)
console.log(x == 5 || y == 5); // false (neither is true)
console.log(!(x == y));       // true (inverse of false)
        

6. Ternary Operator

A shorthand for the if...else statement.

Syntax

condition ? value_if_true : value_if_false

Example

let age = 20;
let type = (age >= 18) ? "Adult" : "Minor";
console.log(type);
        

7. Typeof Operator

The typeof operator returns the type of a variable or an expression.

console.log(typeof "John"); // string
console.log(typeof 3.14);   // number
console.log(typeof true);   // boolean
console.log(typeof [1,2]);  // object (arrays are objects)
console.log(typeof {x:1});  // object
        

8. Comparison Table: == vs ===