Validating date input is a common task when building modern javascript applications, especially when you need code that is easy to read and safe to reuse. As the creator of CoreUI and a developer with over 25 years of experience, I usually prefer the simplest built-in approach that stays explicit in real production code. Use Number.isNaN(date.getTime()) to verify whether a JavaScript Date instance contains a valid timestamp. This keeps the solution approachable while still being reliable enough for components, utilities, and data transformation logic. Below I will show the core snippet first, explain why it works, and point out the most important implementation detail to keep in mind.