NullableInsertKeysKeys of R whose InsertType values can be null or undefined. type NullableInsertKeys<R> = [K in keyof R]: IfNullable<InsertType<R[K]>, K>[keyof R];§Type Parameters§R[src]§Type§[K in keyof R]: IfNullable<InsertType<R[K]>, K>[keyof R][src]