Skip to content

Function: ensureUnreachable

core.ensureUnreachable

ensureUnreachable(value, message?): never

Helper for TypeScript to make sure that handling of code forks is exhaustive, most commonly with a switch statement.

Example

enum MyEnum {
  Foo = 'Foo',
  Bar = 'Bar',
}

function handleEnum(value: MyEnum) {
  switch(value) {
    case MyEnum.Foo:
      return 'foo';
    case MyEnum.Bar:
      return 'bar';
    default:
      // This code is unreachable since the two cases above are exhaustive.
      // However, if a third value were added to MyEnum, TypeScript would flag
      // an error at this line, informing you that you need to update this piece of code.
      return ensureUnreachable(value);
  }
}

Parameters

Name Type
value never
message? string

Returns

never

Defined in

helpers/ensure.ts:29