Knowledge Check

Property presence guard

Which operator can narrow a union by checking whether a property exists?

What this task practices

Property presence guard is a knowledge check interview exercise that trains prompt interpretation, explicit assumptions, a concrete response, and a clear explanation of tradeoffs. The catalog marks it as medium difficulty. It focuses on Frontend Language Browser, Ts Types Narrowing. The signed-in workspace provides the tools for the round and evaluates the attempt against task-specific criteria. Reference solutions, hidden checks, evaluator instructions, and candidate work remain private.