JavaScript Operators

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Example

Assign values to variables and add them together:

var x = 5;         // assign the value 5 to xvar y = 2;         // assign the value 2 to yvar z = x + y;     // assign the value 7 to z (x + y)

Try it Yourself »

The assignment operator (=) assigns a value to a variable.

Assignment

var x = 10;

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The addition operator (+) adds numbers:

Adding

var x = 5;
var y = 2;
var z = x + y;

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The multiplication operator (*) multiplies numbers.

Multiplying

var x = 5;
var y = 2;
var z = x * y;

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JavaScript Arithmetic Operators

Arithmetic operators are used to perform arithmetic on numbers:

Operator	Description
+	Addition
-	Subtraction
*	Multiplication
/	Division
%	Modulus (Division Remainder)
++	Increment
--	Decrement

Arithmetic operators are fully described in the JS Arithmetic chapter.

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JavaScript Assignment Operators

Assignment operators assign values to JavaScript variables.

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

The addition assignment operator (+=) adds a value to a variable.

Assignment

var x = 10;
x += 5;

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Assignment operators are fully described in the JS Assignment chapter.

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JavaScript String Operators

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

Example

var txt1 = "John";
var txt2 = "Doe";
var txt3 = txt1 + " " + txt2;

The result of txt3 will be:

John Doe

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

Example

var txt1 = "What a very ";
txt1 += "nice day";

The result of txt1 will be:

What a very nice day

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

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Adding Strings and Numbers

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

Example

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

The result of x, y, and z will be:

10
55
Hello5

Try it Yourself »

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

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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

Comparison operators are fully described in the JS Comparisons chapter.

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JavaScript Logical Operators

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

Logical operators are fully described in the JS Comparisons chapter.

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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

Type operators are fully described in the JS Type Conversion chapter.

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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
<<	Zero fill left shift	5 << 1	0101 << 1	1010	10
>>	Signed right shift	5 >> 1	0101 >> 1	0010	2
>>>	Zero fill 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

Bitwise operators are fully described in the JS Bitwise chapter.

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Test Yourself with Exercises!

Exercise 1 »  Exercise 2 »  Exercise 3 »  Exercise 4 »  Exercise 5 »