apps-script-utils 2.1.1 Help

requireSymbol

function requireSymbol(value: unknown, message: string = "Expected a symbol."): symbol;

Registered symbols from Symbol.for and the well-known symbols both pass; nothing else does.

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 symbol."

string

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

Returns

symbol — the same value, typed as a symbol.

Throws

Exception

Condition

IllegalArgumentException

the value is not a symbol.

Examples

What passes and what does not

requireSymbol(Symbol("id")); // => Symbol("id") requireSymbol(Symbol.iterator); // => Symbol.iterator requireSymbol("id"); // throws IllegalArgumentException requireSymbol(null); // throws IllegalArgumentException

See also

Source

src/lang/base/requireSymbol.ts

23 September 2026
requireStringrequireUndefined

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