Form Validation

For many programmers, TDD makes sense when it involves toy programs that they learn in a training environment. But they find it hard to join the dots when they are faced with the complexity of real-world programs. The purpose of this part of this book is for you to apply the techniques you’ve learned to real-world applications.

This chapter takes a somewhat self-indulgent journey into form validation. Normally, with React, you’d reach for a ready-made form library that handles validation for you. But in this chapter, we’ll hand-craft our own validation logic, as an example of how real-world complexity can be conquered with TDD.

You will uncover an important architectural principle when dealing with frameworks such as React: take every opportunity to move logic out of framework-controlled components and into plain JavaScript objects.

In this chapter, we will cover the following topics:

• Performing client-side validation
• Handling...