requireString

function requireString(value: unknown, message?: string): string;

The test is typeof value === "string", so the empty string passes and a String object, being an object, does not.

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)	`string`	The message of the exception. A default is used when omitted.

Returns

string — the same value, typed as a string.

Throws

Exception	Condition
`InvalidStringException`	the value is not a string.

Examples

What passes and what does not

requireString(""); // => ""
requireString("abc"); // => "abc"
requireString(1); // throws InvalidStringException
requireString(null); // throws InvalidStringException

Source

src/lang/base/requireString.ts

23 September 2026

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

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