By the end of this lesson, you should be able to do the following:
- Understand the importance of validation in HTML forms.
- Understand Constraint Validation API for more control over form validation.
It’ll also prove beneficial to go through the Constraint Validation docs.
Go back to your ‘Library’ project and add simple validation to that form! Don’t let your users submit without filling in all the fields! Don’t forget to use your Git workflow skills you learned in this foundations lesson to make a new branch, work on your feature and merge it back to main when it’s all done.
Build a browser form which collects Email, Country, Zip Code, Password and Password Confirmation fields. It should use live inline validation to inform the user whether a field is properly filled in or not. That means highlighting a field red and providing a helpful error message until it has been filled in properly.
- Set up a blank HTML document
- Think about how you would set up the different form elements and their accompanying validators. What objects and functions will you need? A few minutes of thought can save you from wasting an hour of coding. The best thing you can do is whiteboard the entire solution before even touching the computer.
- Write the simple form elements.
- Test out all possible cases.
- Don’t forget to style validations with CSS by using the
This section contains questions for you to check your understanding of this lesson. If you’re having trouble answering the questions below on your own, review the material above to find the answer.
- Understand the importance of validating HTML forms before submitting them to a server.
- Understand forms can also be validated without using Constraint Validation API, which is useful in certain cases.