requireSafeInteger

function requireSafeInteger(value: unknown, message: string = "Expected a safe integer."): number;

An integer that an IEEE-754 double represents exactly. Beyond that range distinct mathematical integers collapse onto the same value and arithmetic quietly stops being exact.

isX and nonX answer a question and never interrupt control flow; requireX and requireNonX hand the value back or throw. The scheme is explained in Validation conventions.

Parameters

Parameter	Type	Description
`value`	`unknown`	The value to validate.
`message` (optional) `= "Expected a safe integer."`	`string`	The message of the exception. A default is used when omitted.

Returns

number — the same value, typed as a safe integer.

Throws

Exception	Condition
`IllegalArgumentException`	the value is not a safe integer.

Examples

What passes and what does not

requireSafeInteger(42); // => 42
requireSafeInteger(Number.MAX_SAFE_INTEGER); // => Number.MAX_SAFE_INTEGER
requireSafeInteger(Number.MAX_SAFE_INTEGER + 2); // throws IllegalArgumentException
requireSafeInteger(1.5); // throws IllegalArgumentException

Source

src/lang/number/requireSafeInteger.ts

23 September 2026

This documentation was generated with AI (Claude) from the library's source code.

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