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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.

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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
4.4
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