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.
Unary plus (+)
Try it
Syntax
+x
Description
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
.
Examples
Usage with numbers
const x = 1; const y = -1; console.log(+x); // 1 console.log(+y); // -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
Specifications
Browser compatibility
Desktop | Mobile | Server | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | Deno | Node.js | |
Unary_plus |
1
|
12
|
1
|
3
|
4
|
1
|
1
|
18
|
4
|
10.1
|
1
|
1.0
|
1.0
|
0.10.0
|
See also
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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Unary_plus