JavaScript Operators

Javascript operators are used to perform different types of mathematical and logical computations.

Examples:

The Assignment Operator = assigns values

The Addition Operator + adds values

The Multiplication Operator * multiplies values

The Comparison Operator > compares values

JavaScript Assignment

The Assignment Operator (=) assigns a value to a variable:

Assignment Examples

let x = 10;

// Assign the value 5 to x
let x = 5;
// Assign the value 2 to y
let y = 2;
// Assign the value x + y to z:
let z = x + y;

JavaScript Addition

The Addition Operator (+) adds numbers:

Adding

let x = 5;
let y = 2;
let z = x + y;

JavaScript Multiplication

The Multiplication Operator (*) multiplies numbers:

Multiplying

let x = 5;
let y = 2;
let z = x * y;

Types of JavaScript Operators

There are different types of JavaScript operators:

  • Arithmetic Operators
  • Assignment Operators
  • Comparison Operators
  • String Operators
  • Logical Operators
  • Bitwise Operators
  • Ternary Operators
  • Type Operators

JavaScript Arithmetic Operators

Arithmetic Operators are used to perform arithmetic on numbers:

Arithmetic Operators Example

let a = 3;
let x = (100 + 50) * a;
Operator Description
+ Addition
- Subtraction
* Multiplication
** Exponentiation (ES2016)
/ Division
% Modulus (Division Remainder)
++ Increment
-- Decrement

 

JavaScript Assignment Operators

Assignment operators assign values to JavaScript variables.

The Addition Assignment Operator (+=) adds a value to a variable.

Assignment

let x = 10;
x += 5;
 
Operator Example Same As
= x = y x = y
+= x += y x = x + y
-= x -= y x = x - y
*= x *= y x = x * y
/= x /= y x = x / y
%= x %= y x = x % y
**= x **= y x = x ** y

 

JavaScript Comparison Operators

Operator Description
== equal to
=== equal value and equal type
!= not equal
!== not equal value or not equal type
> greater than
< less than
>= greater than or equal to
<= less than or equal to
? ternary operator

 

JavaScript String Comparison

All the comparison operators above can also be used on strings:

Example

let text1 = "A";
let text2 = "B";
let result = text1 < text2;

Note that strings are compared alphabetically:

Example

let text1 = "20";
let text2 = "5";
let result = text1 < text2;

JavaScript String Addition

The + can also be used to add (concatenate) strings:

Example

let text1 = "John";
let text2 = "Doe";
let text3 = text1 + " " + text2;

The += assignment operator can also be used to add (concatenate) strings:

Example

let text1 = "What a very ";
text1 += "nice day";

The result of text1 will be:

What a very nice day

Note

When used on strings, the + operator is called the concatenation operator.

Adding Strings and Numbers

Adding two numbers, will return the sum, but adding a number and a string will return a string:

Example

let x = 5 + 5;
let y = "5" + 5;
let z = "Hello" + 5;

The result of x, y, and z will be:

10
55
Hello5

Note

If you add a number and a string, the result will be a string!

JavaScript Logical Operators

Operator Description
&& logical and
|| logical or
! logical not

 

JavaScript Type Operators

Operator Description
typeof Returns the type of a variable
instanceof Returns true if an object is an instance of an object type

 

JavaScript Bitwise Operators

Bit operators work on 32 bits numbers.

Any numeric operand in the operation is converted into a 32 bit number. The result is converted back to a JavaScript number.

Operator Description Example Same as Result Decimal
& AND 5 & 1 0101 & 0001 0001  1
| OR 5 | 1 0101 | 0001 0101  5
~ NOT ~ 5  ~0101 1010  10
^ XOR 5 ^ 1 0101 ^ 0001 0100  4
<< left shift 5 << 1 0101 << 1 1010  10
>> right shift 5 >> 1 0101 >> 1 0010   2
>>> unsigned right shift 5 >>> 1 0101 >>> 1 0010   2

The examples above uses 4 bits unsigned examples. But JavaScript uses 32-bit signed numbers.
Because of this, in JavaScript, ~ 5 will not return 10. It will return -6.
~00000000000000000000000000000101 will return 11111111111111111111111111111010