JavaScript Operators — Interview Questions & Answers

Ques: What are Operators in JavaScript?

Ans: Operators are symbols used to perform operations on values and variables, such as addition, comparison, or logic.

Example:

let a = 10, b = 5;
console.log(a + b); // 15

Ques: What are the different types of operators in JavaScript?

Ans: JavaScript provides several types of operators:

Type	Example	Description
Arithmetic	+ - * / % **	Perform math operations
Assignment	= += -= *= /=	Assign values
Comparison	== === != !== > < >= <=	Compare values
Logical	`&&
Bitwise	`&	^ ~ << >> >>>`
Ternary	? :	Conditional check
Type	typeof, instanceof	Check data types
String	+, +=	Concatenate strings

Ques: What are arithmetic operators?

Ans: These are used to perform mathematical calculations.

Operator	Description	Example	Output
+	Addition	5 + 2	7
-	Subtraction	5 - 2	3
*	Multiplication	5 * 2	10
/	Division	10 / 2	5
%	Modulus (Remainder)	10 % 3	1
**	Exponentiation	2 ** 3	8

Example:

let x = 10;
x++;
console.log(x); // 11
x--;
console.log(x); // 10

Ques: What are assignment operators?

Ans: They are used to assign or update values to variables.

Operator	Example	Equivalent To
=	x = 5	x = 5
+=	x += 3	x = x + 3
-=	x -= 2	x = x - 2
*=	x *= 2	x = x * 2
/=	x /= 2	x = x / 2
%=	x %= 2	x = x % 2

Example:

let num = 10;
num += 5;
console.log(num); // 15

Ques: What are comparison operators used for?

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

Operator	Description	Example	Output
==	Equal to	5 == '5'	true
===	Strict equal to	5 === '5'	false
!=	Not equal to	5 != '5'	false
!==	Strict not equal to	5 !== '5'	true
>	Greater than	6 > 3	true
<	Less than	2 < 5	true
>=	Greater than or equal	5 >= 5	true
<=	Less than or equal	4 <= 6	true

Ques: What are logical operators?

Ans: Logical operators combine or invert conditions and return a boolean (true / false).

Operator	Description	Example	Result
&&	Logical AND	(5 > 2 && 6 > 3)	true
`		`	Logical OR
!	Logical NOT	!(5 > 2)	false

Example:

let age = 25;
if (age >= 18 && age <= 30) {
  console.log("Eligible");
}

Ques: What are bitwise operators?

Ans: These perform operations at the binary (bit) level.

Operator	Description	Example	Result
&	AND	5 & 1	1
`	`	OR	`5
^	XOR	5 ^ 1	4
~	NOT	~5	-6
<<	Left shift	5 << 1	10
>>	Right shift	5 >> 1	2

Ques: What is the ternary operator?

Ans: The ternary operator is a shortcut for if...else statements.

Syntax:

condition ? value_if_true : value_if_false;

Example:

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

Ques: What are type operators?

Ans: Used to check data types or relationships of objects.

Operator	Description	Example	Output
typeof	Checks data type	typeof 42	"number"
instanceof	Checks instance	arr instanceof Array	true

Example:

console.log(typeof "Hello"); // string
console.log(typeof null); // object
console.log([1, 2] instanceof Array); // true

Ques: What are string operators?

Ans: The + and += operators are used to concatenate strings.

Example:

let str1 = "Hello";
let str2 = "World";
console.log(str1 + " " + str2); // "Hello World"

Ques: What is operator precedence?

Ans: It defines the order in which operations are performed.

Example:

let result = 10 + 5 * 2;
console.log(result); // 20 (Multiplication before Addition)

Ques: What’s the difference between == and ===?

• == → Compares values only (performs type conversion).
• === → Compares value and data type (strict).

Example:

0 == false; // true
0 === false; // false

Ques: What will "5" + 2 and "5" - 2 return?

"5" + 2; // "52" (string concatenation)
"5" - 2; // 3 (string converted to number)

Ques: What is typeof null?

Ans: Returns "object" — this is a known JavaScript bug.

Ques: What is operator associativity?

Ans: It defines direction of execution —

• Left-to-right (+, , , /)
• Right-to-left (=, *)