Modern websites require a lot of information to function as intended. Information like our usernames, passwords, “friends”, “likes”, credit card information, and shopping orders all have to be provided by users on the front-end and sent to the web applications’ servers so they can be processed. This information is used to create a personalized experience for the user.

User information is traditionally collected using HTML forms. If you’ve ever entered text in a website, selected from options on a list, or checked boxes and then hit enter or pressed a button, you likely filled out and submitted an HTML form!

In order for the data submitted through forms to be useful, it’s essential that the information is valid—if you were allowed to accidentally submit your last name where your address was expected, your package would never show up!

The process of checking that the information submitted through a form adheres to expectations is called form validation. In this lesson, we’ll explore the different techniques for validating form inputs.


Take a look at the form provided. It’s a bare-bones HTML page with no validation. You can play around with it and get to know the different types of inputs on an HTML form.

Think about any of the forms you’ve submitted today—did you log into any sites? Use a search bar? Buy something online?

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