Question: Runtime/Build time? about tsafe HOT 1 CLOSED

Hi @vernak2539, I am sorry to disappoint you but if you are referring to assert(is<T>(val)) there is no test actually performed. You are just saying "trust me typescript I know val is of type T. If you where wrong you won't get build or runtime error when evaluating the assert statement.

If there is a simple test that discriminate the type of your variable that TypeScript can understand, use it instead of is this way you will get runtime validation.

If there isn't such a test and you want to have an error at runtime in case you where wrong with your assertion you can use typeGuard.

In this case you probably want to put a message for the exception:

Be careful though, it is up to you to make sure that your check obj.id.startsWith("foo-") actually validate that obj is of type Foo.

from tsafe.