Operators and Expressions

 

Operators in JavaScript allow you to perform operations on variables and values, creating expressions that produce new values.

Arithmetic Operators

Used to perform basic math operations:

Operator	Description	Example	Result
+	Addition	5 + 3	8
-	Subtraction	5 - 3	2
*	Multiplication	5 * 3	15
/	Division	10 / 2	5
%	Modulus (remainder)	7 % 3	1
++	Increment	let a = 1; a++;	2
--	Decrement	let b = 2; b--;	1

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Assignment Operators

Used to assign values to variables, often combined with arithmetic:

Operator	Description	Example	Result
=	Assign	x = 10	x becomes 10
+=	Add and assign	x += 5	x = x + 5
-=	Subtract and assign	x -= 3	x = x - 3
*=	Multiply and assign	x *= 2	x = x * 2
/=	Divide and assign	x /= 4	x = x / 4
%=	Modulus and assign	x %= 3	x = x % 3

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Comparison Operators

Compare values and return a Boolean (true or false):

Operator	Description	Example	Result
==	Equal (value only)	5 == '5'	true
===	Equal (value and type)	5 === '5'	false
!=	Not equal (value only)	5 != 10	true
!==	Not equal (value/type)	5 !== '5'	true
<	Less than	3 < 5	true
>	Greater than	10 > 7	true
<=	Less than or equal	5 <= 5	true
>=	Greater than or equal	7 >= 10	false

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Logical Operators

Used to combine or invert Boolean values:

Operator	Description	Example	Result
&&	Logical AND	true && false	false
`		`	Logical OR
!	Logical NOT	!true	false

String Concatenation

The + operator can also join (concatenate) strings:

let greeting = "Hello, " + "world!";

console.log(greeting);  // Output: Hello, world!

You can also combine variables and strings:

let name = "Alice";

console.log("Hi, " + name + "!");  // Output: Hi, Alice!