Operators (JavaScript)

Other Versions

JavaScript has a full range of operators, including arithmetic, logical, bitwise, assignment, as well as some miscellaneous operators.

Computational Operators

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Description	Symbol
Unary negation	-
Increment	++
Decrement	--
Multiplication	*
Division	/
Modulus arithmetic	%
Addition	+
Subtraction	-

Logical Operators

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Description	Symbol
Logical NOT	!
Less than	<
Greater than	>
Less than or equal to	<=
Greater than or equal to	>=
Equality	==
Inequality	!=
Logical AND	&&
Logical OR	||
Conditional (ternary)	?:
Comma	,
Strict Equality	===
Strict Inequality	!==

Bitwise Operators

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Description	Symbol
Bitwise NOT	~
Bitwise Left Shift	<<
Bitwise Right Shift	>>
Unsigned Right Shift	>>>
Bitwise AND	&
Bitwise XOR	^
Bitwise OR	|

Assignment Operators

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Description	Symbol
Assignment	=
Compound Assignment	OP= (such as += and &=)

Miscellaneous Operators

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Description	Symbol
delete	delete
typeof	typeof
void	void
instanceof	instanceof
new	new
in	in

The difference between == (equality) and === (strict equality) is that the equality operator will coerce values of different types before checking for equality. For example, comparing the string "1" with the number 1 will compare as true. The strict equality operator, on the other hand, will not coerce values to different types, and so the string "1" will not compare as equal to the number 1.

Primitive strings, numbers, and Booleans are compared by value. If they have the same value, they will compare as equal. Objects (including Array, Function, String, Number, Boolean, Error, Date and RegExp objects) compare by reference. Even if two variables of these types have the same value, they will only compare as true if they refer to exactly the same object.

For example:

JavaScript

// Two primitive strings with the same value.
var string1 = "Hello";
var string2 = "Hello";

// Two String objects, with the same value.
var StringObject1 = new String(string1);
var StringObject2 = new String(string2);

// This will be true.
if (string1 == string2)
     // do something (this will be executed)

// This will be false.
if (StringObject1 == StringObject2)
    // do something (this will not be executed)

// To compare the value of String objects, 
// use the toString() or valueOf() methods.
if (StringObject1.valueOf() == StringObject2)
     // do something (this will be executed)