requireService

function requireService<T>(
  service: T | null | undefined,
  message: string = "Service is not defined."
): T;

An advanced service that was never enabled is simply an undefined global, and the failure that follows is a ReferenceError far from its cause. This turns it into a named exception with a message that says what to switch on.

Parameters

Parameter	Type	Description
`service`	`T \\| null \\| undefined`	The service to check.
`message` (optional) `= "Service is not defined."`	`string`	The message of the exception. A default is used when omitted.

Returns

T — the same service.

Throws

Exception	Condition
`ServiceIsNotDefinedException`	the service is `null` or `undefined`.

Examples

In use

// An advanced service is a global that only exists once it has been enabled.
const directory = requireService(AdminDirectory, "Enable the Admin SDK service.");

Source

src/appsscript/requireService.ts

23 September 2026

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

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