Yup
Yup is a JavaScript schema builder for value parsing and validation, commonly used in form validation for web applications. It provides a declarative API to define object schemas with built-in validation rules, such as required fields, string patterns, and number ranges. It integrates seamlessly with form libraries like Formik and React Hook Form to validate user input in frontend development.
Developers should learn Yup when building forms in React or other JavaScript frameworks to ensure data integrity and user-friendly validation feedback. It is particularly useful for complex validation scenarios, such as conditional rules, nested objects, or custom validation logic, reducing boilerplate code compared to manual validation. Use cases include sign-up forms, data submission interfaces, and configuration settings where input validation is critical.