Operators

What is an operator?

A symbol used to perform a built-in function on one - it is then called unary operator- or more operands (data values).

JavaScript has the following operators:

Assignment:
An assignment operator assigns a value to its left operand based on the value of its right operand or both left and right operands.

Comparison:
A comparison operator compares its operands of various data types and returns a Boolean value (true or false.)

Arithmetic:
Arithmetic operators take numerical values (either literals or variables) as their operands and return a single numerical value.

String:
String operators take string values (either literals or variables) as their operands and return a single string value.

Logical:
Logical operators take Boolean (logical) values as operands and return a Boolean value.

Bitwise:
Arithmetic operators take numerical values (either literals or variables) as their operands and return a single numerical value. Bitwise operators work on the bits representing these numerical values . Those numerical values are all represented as 32 bit integers.

Special operators:
Each special operator is entirely different from the rest.

Operators Example

Assignment Operators
Operator	Operation	Description	Usage
=		Assigns the value of the second operand to the first operand.	a = b
+=		Adds 2 numbers and assigns the result to the first.	a += b
-=		Subtracts 2 numbers and assigns the result to the first.	a -= b
*=		Multiplies 2 numbers and assigns the result to the first.	a *= b
/=		Divides 2 numbers and assigns the result to the first.	a /= b
%=		Computes the modulus of 2 numbers and assigns the result to the first.	a %= b
&=		Performs a bitwise AND and assigns the result to the first operand.
^=		Performs a bitwise XOR and assigns the result to the first operand.
\|=		Performs a bitwise OR and assigns the result to the first operand.
<<=		Performs a left shift and assigns the result to the first operand.
>>=		Performs a sign-propagating right shift and assigns the result to the first operand.
>>>=		Performs a zero-fill right shift and assigns the result to the first operand.

Comparison Operators
Operator	Operation	Description	Usage
==		Returns true if the operands are equal.	a == b
!=		Returns true if the operands are not equal.	a != b
>		Returns true if left operand is greater than right operand.	a > b
>=		Returns true if left operand is greater than or equal to right operand.	a >= b
<		Returns true if left operand is less than right operand.	a < b
<=		Returns true if left operand is less than or equal to right operand.	a <= b

Arithmetic Operators
Operator	Operation	Description	Usage
+	Addition	Adds 2 numbers.	a + b
++	Increment	Adds one to a variable representing a number (returning either the new or old value of the variable)	a++ or ++a
-	Unary negation, subtraction	As a unary operator, negates the value of its argument. As a binary operator, subtracts 2 numbers.	a = -b
--	Decrement	Subtracts one from a variable representing a number (returning either the new or old value of the variable)	a-- or --a
*	Multiplication	Multiplies 2 numbers.	a * b
/	Division	Divides 2 numbers.	a/b
%	Modulus	Computes the integer remainder of dividing 2 numbers.	a % b

String Operators
Operator	Operation	Description	Usage
+	String addition	Concatenates 2 strings.	a + b
+=	String assignment and addition	Concatenates 2 strings and assigns the result to the first operand.	a += b

Logical Operators
Operator	Operation	Description	Usage
&&	Logical AND	Returns true if both logical operands are true. Otherwise, returns false.	expr1 && expr2
\|\|	Logical OR	Returns true if either logical expression is true. If both are false, returns false.	expr1 \|\| expr2
!	Logical negation	If its single operand is true, returns false; otherwise, returns true.	!expr

Bitwise Operators
Operator	Operation	Description	Usage
&	Bitwise AND	Returns a one in each bit position if bits of both operands are ones.	a & b
^	Bitwise XOR	Returns a one in a bit position if bits of one but not both operands are one.	a ^ b
\|	Bitwise OR	Returns a one in a bit if bits of either operand is one.	a \| b
~	Bitwise NOT	Flips the bits of its operand.	~ a
<<	Left shift	Shifts its first operand in binary representation the number of bits to the left specified in the second operand, shifting in zeros from the right.	a << b
>>	Sign-propagating right shift	Shifts the first operand in binary representation the number of bits to the right specified in the second operand, discarding bits shifted off.	a >> b
>>>	Zero-fill right shift	Shifts the first operand in binary representation the number of bits to the right specified in the second operand, discarding bits shifted off, and shifting in zeros from the left.	a >>> b

Special Operators
Operator	Operation	Description	Usage
?:		Lets you perform a simple "if...then...else"	condition ? expr1 : expr2
,		Evaluates two expressions and returns the result of the second expression.	expr1, expr2
delete		Lets you delete an object property or an element at a specified index in an array.	delete object.property delete object[index]
new		Lets you create an instance of a user-defined object type or of one of the built-in object types.	objectName = new objectType (param1 [,param2] ...[,paramN])
this		Keyword that you can use to refer to the current object.	this[.propertyName]
typeof		Returns a string indicating the type of the unevaluated operand.	typeof operand typeof (operand)
void		The void operator specifies an expression to be evaluated without returning a value.	javascript:void (expression) javascript:void expression