Chapter 11. Validating forms
This chapter covers
- Using built-in form validators
- Creating custom validators
- Handling sync and async validation
The user fills out a form and clicks Submit, expecting that the app will process the data in some way. In web applications, the data is usually sent to the server. Often, the user receives some data back (for example, search results), but sometimes, the data is just saved in the server’s storage (for example, creating a new order). In any case, the data should be valid so the server’s software can do its job properly.
For example, an app can’t log in a user unless they’ve provided a user ID and a password in the login form. Both fields are required—otherwise, the form isn’t valid. You shouldn’t even ...
Get Angular Development with TypeScript, Second Edition now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
