JavaScript Operators

JavaScript operators are the foundation of performing operations and comparisons in the language. They let you manipulate data, evaluate conditions, and build complex logic. In this post, we’ll cover the four primary types of operators: arithmetic, comparison, logical, and assignment.

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Arithmetic Operators

Arithmetic operators are used to perform mathematical calculations.

Operator	Description	Example	Result
+	Addition	5 + 3	8
-	Subtraction	10 - 6	4
*	Multiplication	4 * 7	28
/	Division	20 / 4	5
%	Modulus (remainder)	10 % 3	1

let a = 20;
let b = 4;
console.log(a + b); // Outputs: 24
console.log(a - b); // Outputs: 16
console.log(a * b); // Outputs: 80
console.log(a / b); // Outputs: 5
console.log(a % b); // Outputs: 0

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Comparison Operators

Comparison operators are used to compare two values and return a boolean (true or false) result.

Operator	Description	Example	Result
==	Equal to (value only)	5 == '5'	true
===	Strict equal to (value + type)	5 === '5'	false
!=	Not equal to (value only)	5 != '6'	true
<	Less than	5 < 10	true
>	Greater than	10 > 5	true

Examples:

console.log(x == y); // Outputs: true (loose equality, checks only value)
console.log(x === y); // Outputs: false (strict equality, checks value and type)
console.log(x != y); // Outputs: false (values are equal)
console.log(x < 10); // Outputs: true
console.log(x > 1); // Outputs: true

Note: Always prefer using === and !== over == and != to avoid unexpected type coercion issues.

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Logical Operators

Logical operators allow you to combine multiple conditions or evaluate logical expressions.

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

Logical AND (&&)

Returns true only if both conditions are true.

let a = true;
let b = false;
console.log(a && b); // Outputs: false
console.log(a && !b); // Outputs: true

Logical OR (||)

Returns true if one or more conditions are true.

let age = 18;
console.log(age > 16 || age < 12); // Outputs: true
console.log(age > 20 || age < 10); // Outputs: false

Logical NOT (!)

Reverses a boolean value.

let isActive = true;
console.log(!isActive); // Outputs: false

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Assignment Operators

Assignment operators are used to assign values to variables. You can perform operations while assigning values.

Operator	Description	Example	Equivalent To
=	Assign	x = 5	—
+=	Add and assign	x += 3	x = x + 3
-=	Subtract and assign	x -= 2	x = x - 2
*=	Multiply and assign	x *= 4	x = x * 4
/=	Divide and assign	x /= 2	x = x / 2
%=	Modulus and assign	x %= 3	x = x % 3

Examples:

let x = 10;
x += 5; // Equivalent to x = x + 5 console.log(x); // Outputs: 15
x *= 2; // Equivalent to x = x * 2 console.log(x); // Outputs: 30
x -= 10; // Equivalent to x = x - 10 console.log(x); // Outputs: 20
x /= 5; // Equivalent to x = x / 5 console.log(x); // Outputs: 4
x %= 3; // Equivalent to x = x % 3 console.log(x); // Outputs: 1

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