4.5 Operators

Operators are symbols that perform operations on values and variables.

Example:

let sum = 10 + 5;

Here:

• 10 and 5 → Operands
• + → Operator

Output:

15

Operators allow JavaScript to perform calculations, compare values, assign data, make decisions, and manipulate variables.

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What are Operators?

Operators allow JavaScript to:

• Perform Calculations
• Compare Values
• Assign Data
• Make Decisions
• Manipulate Bits
• Work with Strings

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Types of Operators

JavaScript provides several categories of operators:

1. Assignment Operators
2. Arithmetic Operators
3. Comparison Operators
4. Logical Operators
5. Bitwise Operators
6. Unary Operators
7. Conditional (Ternary) Operator
8. String Operators

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Assignment Operators

Assignment operators assign values to variables.

Basic Assignment (=)

let age = 21;

Meaning:

Store 21 inside age

Example

let x = 10;

console.log(x);

Output

10

---

Addition Assignment (+=)

let x = 10;

x += 5;

Equivalent to

x = x + 5;

Output

15

---

Subtraction Assignment (-=)

let x = 10;

x -= 3;

Equivalent to

x = x - 3;

Output

7

---

Multiplication Assignment (*=)

let x = 10;

x *= 2;

Output

20

---

Division Assignment (/=)

let x = 10;

x /= 2;

Output

5

---

Modulus Assignment (%=)

let x = 10;

x %= 3;

Output

1

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Assignment Operators Summary

Operator	Example	Equivalent
=	x = 5	Assign value
+=	x += 2	x = x + 2
-=	x -= 2	x = x - 2
*=	x *= 2	x = x * 2
/=	x /= 2	x = x / 2
%=	x %= 2	x = x % 2

---

Arithmetic Operators

Arithmetic operators perform mathematical calculations.

Addition (+)

10 + 5;

Output

15

---

Subtraction (-)

10 - 5;

Output

5

---

Multiplication (*)

10 * 5;

Output

50

---

Division (/)

10 / 5;

Output

2

---

Modulus (%)

Returns the remainder after division.

10 % 3;

Output

1

---

Exponentiation (**)

Raises a number to a power.

2 ** 3;

Output

8

Equivalent to

2 × 2 × 2

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Arithmetic Operators Summary

Operator	Meaning
+	Addition
-	Subtraction
*	Multiplication
/	Division
%	Modulus
**	Exponentiation

---

Comparison Operators

Comparison operators compare two values.

The result is always:

• true
• false

---

Equal (==)

5 == "5";

Output

true

JavaScript converts the values before comparing them.

---

Strict Equal (===)

5 === "5";

Output

false

No type conversion occurs.

Best Practice: Always prefer === over ==.

---

Not Equal (!=)

5 != 3;

Output

true

---

Strict Not Equal (!==)

5 !== "5";

Output

true

---

Greater Than (>)

10 > 5;

Output

true

---

Less Than (<)

5 < 10;

Output

true

---

Greater Than or Equal (>=)

10 >= 10;

Output

true

---

Less Than or Equal (<=)

5 <= 10;

Output

true

---

Comparison Operators Summary

Operator	Meaning
==	Equal
===	Strict Equal
!=	Not Equal
!==	Strict Not Equal
>	Greater Than
<	Less Than
>=	Greater Than or Equal
<=	Less Than or Equal

---

Logical Operators

Logical operators combine multiple conditions.

---

AND (&&)

Returns true only if both conditions are true.

true && true;

Output

true

Example

age >= 18 && age <= 60;

Meaning:

Age Between 18 and 60

---

OR (||)

Returns true if at least one condition is true.

true || false;

Output

true

Example

role === "admin" || role === "manager";

---

NOT (!)

Reverses a boolean value.

!true;

Output

false

Example

let isLoggedIn = false;

console.log(!isLoggedIn);

Output

true

---

Logical Operators Summary

Operator	Meaning
&&	AND
||	OR
!	NOT

---

Bitwise Operators

Bitwise operators work directly with binary numbers.

These are mainly used in low-level programming and are less common in everyday web development.

---

AND (&)

5 & 1;

Binary

5 = 101
1 = 001
--------
    001

Output

1

---

OR (|)

5 | 1;

Output

5

---

XOR (^)

5 ^ 1;

Output

4

---

NOT (~)

~5;

Output

-6

---

Left Shift (<<)

5 << 1;

Output

10

---

Right Shift (>>)

10 >> 1;

Output

5

---

Bitwise Operators Summary

Operator	Meaning
&	AND
|	OR
^	XOR
~	NOT
<<	Left Shift
>>	Right Shift

---

Unary Operators

Unary operators work with a single operand.

---

Unary Plus (+)

Converts a value into a number.

+"100";

Output

100

---

Unary Minus (-)

-"100";

Output

-100

---

Increment (++)

Adds one.

let x = 5;

x++;

Output

6

---

Decrement (--)

Subtracts one.

let x = 5;

x--;

Output

4

---

typeof

Returns the data type.

typeof "Hello";

Output

string

---

delete

Removes an object property.

const user = {

    name: "Samir"

};

delete user.name;

---

Unary Operators Summary

Operator	Meaning
+	Convert to Number
-	Negative Value
++	Increment
--	Decrement
typeof	Data Type
delete	Remove Property

---

Conditional (Ternary) Operator

The ternary operator is a shorter way of writing an if...else statement.

Syntax

condition
? valueIfTrue
: valueIfFalse;

---

Example

let age = 20;

let result =
age >= 18
? "Adult"
: "Minor";

Output

Adult

Equivalent if...else

if (age >= 18) {

    result = "Adult";

} else {

    result = "Minor";

}

---

Another Example

const isLoggedIn = true;

const message =
isLoggedIn
? "Welcome"
: "Login First";

Output

Welcome

---

String Operators

String operators combine and manipulate text.

---

Concatenation (+)

"Hello" + " World";

Output

Hello World

---

Example

let firstName = "Samir";
let lastName = "Niroula";

let fullName =
firstName + " " + lastName;

Output

Samir Niroula

---

Concatenation Assignment (+=)

let text = "Hello";

text += " World";

Output

Hello World

---

Template Literals (Recommended)

Instead of

let fullName =
firstName + " " + lastName;

Use

let fullName =
`${firstName} ${lastName}`;

Template literals are cleaner and easier to read.

---

Complete Example

let age = 21;

age += 1;

let status =
age >= 18
? "Adult"
: "Minor";

console.log(status);

Output

Adult

---

Operator Precedence

JavaScript follows mathematical precedence rules.

Example

10 + 5 * 2;

Output

20

Because:

5 × 2 = 10

10 + 10 = 20

---

Parentheses

Parentheses change the order of evaluation.

(10 + 5) * 2;

Output

30

---

Summary

Category	Operators
Assignment	=, +=, -=, *=, /=, %=
Arithmetic	+, -, *, /, %, **
Comparison	==, ===, !=, !==, >, <, >=, <=
Logical	&&, ||, !
Bitwise	&, |, ^, ~, <<, >>
Unary	+, -, ++, --, typeof, delete
Conditional	?:
String	+, +=

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Key Takeaway

Operators allow JavaScript to perform calculations, comparisons, assignments, and logical decisions.

The most commonly used operators in modern JavaScript are:

+
-
*
/
===
!==
>
<
&&
||
++
--
?:

Remember:

Assignment  → Store Values
Arithmetic  → Perform Math
Comparison  → Compare Values
Logical     → Combine Conditions
Unary       → Modify Single Values
Ternary     → Short if...else
String      → Join Text

Learning these operators is essential because they are used in almost every JavaScript program.