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MDN / 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.

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

+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 [ 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/

{{InteractiveExample(“JavaScript Demo: Unary plus (+) operator”, “taller”)}}

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

+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 {{jsxref(“NaN”)}}/ Unlike other arithmetic operators, which work with both numbers and BigInts, using the + operator on BigInt values throws a {{jsxref(“TypeError”)}}/

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

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

{{InteractiveExample(“JavaScript Demo: Unary plus (+) operator”, “taller”)}}

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

+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 {{jsxref(“NaN”)}}/ Unlike other arithmetic operators, which work with both numbers and BigInts, using the + operator on BigInt values throws a {{jsxref(“TypeError”)}}/

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

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

{{InteractiveExample(“JavaScript Demo: Unary plus (+) operator”, “taller”)}}

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

+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 {{jsxref(“NaN”)}}/ Unlike other arithmetic operators, which work with both numbers and BigInts, using the + operator on BigInt values throws a {{jsxref(“TypeError”)}}/

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

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

{{InteractiveExample(“JavaScript Demo: Unary plus (+) operator”, “taller”)}}

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

+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 {{jsxref(“NaN”)}}/ Unlike other arithmetic operators, which work with both numbers and BigInts, using the + operator on BigInt values throws a {{jsxref(“TypeError”)}}/

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

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

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

Specifications

Browser compatibility

See also