validateNonNegativeInteger

Validates a value as a non-negative integer (zero or greater).

This helper never throws and never mutates input. Returns a structured ValidationResult for composable validation pipelines.

Signature

function validateNonNegativeInteger(
    value: unknown,
    field: string
): ValidationResult<number>

Parameters

Name	Type	Description
value	unknown	The value to validate.
field	string	The field name for error reporting.

Returns

• { ok: true; value: number }: If valid.
• { ok: false; field: string; message: string }: If invalid.

Examples

validateNonNegativeInteger(0, 'age');       // → { ok: true, value: 0 }
validateNonNegativeInteger(42, 'count');    // → { ok: true, value: 42 }
validateNonNegativeInteger(-1, 'index');    // → { ok: false, field: 'index', message: 'Value must be a non-negative integer' }
validateNonNegativeInteger(3.14, 'pages');  // → { ok: false, field: 'pages', message: 'Value must be a non-negative integer' }
validateNonNegativeInteger("5", 'total');   // → { ok: false, field: 'total', message: 'Value must be a non-negative integer' }

Notes

Only integer numbers greater than or equal to zero (0) are valid.

Fractional numbers, negative numbers, strings, NaN, Infinity, -Infinity and non-numeric types fail.

Use normalizeNonNegativeInteger before validation if input may be a string.