toNumber()

toNumber(value, defaultValue?): number

Converts any value to a number with fallback handling.

note

Booleans convert to 1/0. Null/undefined/Symbol return default. NaN returns default.

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Parameters

value: unknown

The value to convert.

defaultValue?: number = 0

Default value if conversion fails.

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Returns: number

A number representation of the value.

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Since

2.0.0

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Note

BigInt values are converted to number (may lose precision for large values).

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Performance

O(1)

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Also known as

parse (Effect) · toFloat (Radashi) · toNumber (Lodash) · ❌ (es-toolkit, Remeda, Ramda, Modern Dash, Antfu)

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Example

toNumber('42');          // => 42
toNumber('3.14');        // => 3.14
toNumber('invalid');     // => 0 (default)
toNumber(true);          // => 1
toNumber(false);         // => 0
toNumber(null);          // => 0 (default)
toNumber('invalid', 10); // => 10 (custom default)
toNumber(10n);           // => 10 (BigInt)

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How it works?

Converts any value to a number with fallback handling.

Conversion Examples

Input	Output
'42'	42
'3.14'	3.14
'invalid'	0 (default)
true	1
false	0
null	0 (default)
10n	10

Custom Default

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Use Cases

Convert inputs safely 📌

Transform various input types to a number, handling NaN and failures gracefully. Critical for processing user input, query parameters, or API response data.

#convert#parse#number#inputs#safe#validation

const page = toNumber(params.page, 1);
const limit = toNumber(params.limit, 20);

Normalize mixed data types

Convert booleans or numeric strings from legacy data sources. Useful for data migration or standardization scripts.

#normalize#mixed#types#conversion#legacy#migration

const count = toNumber(data.count); // Handles "10", 10, true (1), or null (0)