Unary plus (+)

The unary plus operator (+) precedes its operand and evaluates to its operand but attempts to convert it into a number, if it isn't already.


Operator: +x


Although unary negation (-) also can convert non-numbers, unary plus is the fastest and preferred way of converting something into a number, because it does not perform any other operations on the number. It can convert string representations of integers and floats, as well as the non-string values true, false, and null. Integers in both decimal and hexadecimal (0x-prefixed) formats are supported. Negative numbers are supported (though not for hex). Using the operator on BigInt values throws a TypeError. If it cannot parse a particular value, it will evaluate to NaN.


Usage with numbers

const x = 1;
const y = -1;

// 1
// -1

Usage with non-numbers

+true  // 1
+false // 0
+null  // 0
+function(val){ return val } // NaN
+1n    // throws TypeError: Cannot convert BigInt value to number


ECMAScript (ECMA-262)
The definition of 'Unary plus operator' in that specification.

Browser compatibility

ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
Unary plus (+)Chrome Full support 1Edge Full support 12Firefox Full support 1IE Full support 3Opera Full support 4Safari Full support 1WebView Android Full support 1Chrome Android Full support 18Firefox Android Full support 4Opera Android Full support 10.1Safari iOS Full support 1Samsung Internet Android Full support 1.0nodejs Full support 0.1.100


Full support
Full support

See also