Unary plus (+)

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

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.

Try it

const x = 1;
const y = -1;

console.log(+x);
// Expected output: 1

console.log(+y);
// Expected output: -1

console.log(+"");
// Expected output: 0

console.log(+true);
// Expected output: 1

console.log(+false);
// Expected output: 0

console.log(+"hello");
// Expected output: NaN

Syntax

js
+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.

Unary plus does the exact same steps as normal number coercion used by most built-in methods expecting numbers. 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). If it cannot parse a particular value, it will evaluate to NaN. Unlike other arithmetic operators, which work with both numbers and BigInts, using the + operator on BigInt values throws a TypeError.

Examples

Usage with numbers

js
const x = 1;
const y = -1;

console.log(+x);
// 1
console.log(+y);
// -1

Usage with non-numbers

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

Specifications

Specification
ECMAScript® 2025 Language Specification
# sec-unary-plus-operator

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobileserver
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
Node.js
Unary plus (+)

Legend

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Full support
Full support

See also