Exponentiation (**)

The exponentiation operator (**) returns the result of raising the first operand to the power of the second operand. It is equivalent to Math.pow, except it also accepts BigInts as operands.

Syntax

Operator: var1 ** var2

Description

The exponentiation operator is right-associative: a ** b ** c is equal to a ** (b ** c).

In most languages, such as PHP, Python, and others that have an exponentiation operator (**), the exponentiation operator is defined to have a higher precedence than unary operators, such as unary + and unary -, but there are a few exceptions. For example, in Bash, the ** operator is defined to have a lower precedence than unary operators.

In JavaScript, it is impossible to write an ambiguous exponentiation expression. That is, you cannot put a unary operator (+/-/~/!/delete/void/typeof) immediately before the base number; doing so will cause a SyntaxError.

-2 ** 2; 
// 4 in Bash, -4 in other languages. 
// This is invalid in JavaScript, as the operation is ambiguous. 


-(2 ** 2); 
// -4 in JavaScript and the author's intention is unambiguous. 

Note that some programming languages use the caret symbol ^ for exponentiation, but JavaScript uses that symbol for the bitwise logical XOR operator.

Examples

Basic exponentiation

2 ** 3   // 8
3 ** 2   // 9
3 ** 2.5 // 15.588457268119896
10 ** -1 // 0.1
NaN ** 2 // NaN

Associativity

2 ** 3 ** 2   // 512
2 ** (3 ** 2) // 512
(2 ** 3) ** 2 // 64

Usage with unary operators

To invert the sign of the result of an exponentiation expression:

-(2 ** 2) // -4

To force the base of an exponentiation expression to be a negative number:

(-2) ** 2 // 4

Specifications

Specification
ECMAScript (ECMA-262)
The definition of 'Exponentiation operator' in that specification.

Browser compatibility

Update compatibility data on GitHub
DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
Exponentiation (**)Chrome Full support 52Edge Full support 14Firefox Full support 52IE No support NoOpera Full support 39Safari Full support 10.1WebView Android Full support 51Chrome Android Full support 52Firefox Android Full support 52Opera Android Full support 41Safari iOS Full support 10.3Samsung Internet Android Full support 6.0nodejs Full support 7.0.0
Full support 7.0.0
Full support 6.5.0
Disabled
Disabled From version 6.5.0: this feature is behind the --harmony runtime flag.

Legend

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See also