requireNonRegExp

function requireNonRegExp<T>(
  value: T | RegExp,
  message: string = "Expected a value that is not a regular expression."
): T;

Identified by its internal tag rather than by instanceof, so a regular expression from another frame is recognised too.

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`	`T \\| RegExp`	The value to validate.
`message` (optional) `= "Expected a value that is not a regular expression."`	`string`	The message of the exception. A default is used when omitted.

Returns

T — the same value, with a regular expression excluded from its type.

Throws

Exception	Condition
`IllegalArgumentException`	the value is a regular expression.

Examples

What passes and what does not

requireNonRegExp("/a/"); // => "/a/"
requireNonRegExp({}); // => {}
requireNonRegExp(/a/); // throws IllegalArgumentException
requireNonRegExp(new RegExp("a")); // throws IllegalArgumentException

Source

src/lang/base/requireNonRegExp.ts

23 September 2026

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

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