You mark a property with ? to make it optional (e.g., name?: string). It may be present or undefined.
Advanced answer
Deep dive
Expanding on the short answer — what usually matters in practice:
Context (tags): optional, types
Explain the "why", not just the "what" (intuition + consequences).
Trade-offs: what you gain/lose (time, memory, complexity, risk).
Edge cases: empty inputs, large inputs, invalid inputs, concurrency.
Examples
A tiny example (an explanation template):
// Example: discuss trade-offs for "how-do-optional-properties-work-in-typescript?"
function explain() {
// Start from the core idea:
// You mark a property with ? to make it optional (e.g., name?: string). It may be present or
}
Common pitfalls
Too generic: no concrete trade-offs or examples.
Mixing average-case and worst-case (e.g., complexity).