Operators in JavaScript

7.1 Operators and Expressions in JavaScript

Expression is any valid unit of code that evaluates to a value

3 + 5 = 8
"Hello" + "World" = "HelloWorld"
true && false = false

We write expressions using operators and values

Arithmatic Operators - Used for mathematical operations

Operator	Description	Example	Result
+	Addition	10 + 5	15
-	Subtraction	10 - 5	5
*	Multiplication	10 * 5	50
/	Division	10 / 5	2
%	Modulus (Remainder)	10 % 3	1
**	Exponentiation	2 ** 3	8

Arithmatic Operators in code

arithmatic.js

let a = 10
let b = 3
console.log("Addition:", a + b)
console.log("Modulo:", a % b)
console.log("Power:", a ** b)

Assignment Operators - Used to assign values to variables

Operator	Description	Example	Result
=	Assignment	x = 10	x = 10
+=	Add and Assign	x += 2	x = x + 2
-=	Subtract and Assign	x -= 3	x = x - 3
*=	Multiply and Assign	x *= 2	x = x * 2
/=	Divide and Assign	x /= 2	x = x / 2

Assignment Operators in code

assignment.js

let score = 20
score += 5
console.log("Score after bonus:", score)

Comparision Operators - Used to compare values then return true or false

Operator	Description	Example	Result
==	Equal (lose)	5 == '5'	true
===	Equal (strict)	5 === '5'	false
!=	Not Equal (loose)	5 != '5'	false
!==	Not Equal (strict)	5 !== '5'	true
>	Greater than	5 > 3	true
<	Less than	3 < 5	true
>=	Greater than or equal to	5 >= 5	true
<=	Less than or equal to	4 <= 5	true

Comparision Operators in code

comparision.js

console.log(10 > 5)       // true
console.log(10 === "10")  // false
console.log(10 == "10")   // true

Logical Operators - Used to combine conditions

Operator	Description	Example	Result
&&	AND	true && false	false
\|\|	OR	true \|\| false	true
!	NOT	!true	false

Logical Operators in code

logical.js

let isLoggedIn = true
let hasPremium = false
console.log(isLoggedIn && hasPremium)  // false
console.log(isLoggedIn || hasPremium)  // true
console.log(!isLoggedIn)               // false