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.
Theunary plus (+) operator precedes its operand and evaluates to itsoperand but attempts toconvert it into a number, if it isn't already.
Try it
const x = 1;const y = -1;console.log(+x);// Expected output: 1console.log(+y);// Expected output: -1console.log(+"");// Expected output: 0console.log(+true);// Expected output: 1console.log(+false);// Expected output: 0console.log(+"hello");// Expected output: NaNSyntax
+xDescription
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 normalnumber coercion used by most built-in methods expecting numbers. It can convert string representations of integers and floats, as well as the non-string valuestrue,false, andnull. 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 toNaN. Unlike other arithmetic operators, which work with both numbers andBigInts, using the+ operator on BigInt values throws aTypeError.
Examples
Usage with numbers
const x = 1;const y = -1;console.log(+x);// 1console.log(+y);// -1Usage with non-numbers
+true // 1+false // 0+null // 0+[] // 0+function (val) { return val; } // NaN+1n // throws TypeError: Cannot convert BigInt value to numberSpecifications
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-unary-plus-operator |