requireUi

function requireUi(
  value: unknown,
  message: string = "Expected a Ui object."
): GoogleAppsScript.Base.Ui;

An Apps Script service object has no constructor a script can test against, so the guard reads the tag the object reports for itself: value.toString() === "Ui". A plain object that reports the same tag passes too, which in practice means a test double.

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 Ui object."`	`string`	The message of the exception. A default is used when omitted.

Returns

GoogleAppsScript.Base.Ui — the same value, typed as a Ui object.

Throws

Exception	Condition
`IllegalArgumentException`	the value is not a Ui object.

Examples

What passes and what does not

const ui = SpreadsheetApp.getUi();

requireUi(ui); // => ui
requireUi({}); // throws IllegalArgumentException
requireUi(null); // throws IllegalArgumentException

Source

src/appsscript/ui/requireUi.ts

23 September 2026

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

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