1.1 Introduction

JavaScript was created for the sole purpose of form validation. Now, that might sound simplistic to you especially considering what we use JavaScript for in today's web applications. But just think about it, in the mid to late 1990s, the people that had Internet service were connected at 33.6 kilobyte per second or 56 kilobits per second. Not very fast at all. So imagine spending several minutes filling out a form, submitting it and then waiting for 20 or 30 seconds, only to be told, that you missed a field or entered something invalid in one of the fields. It was frustrating, and so JavaScript was created to alleviate that frustration. Now form validation has never been fun. And it's interesting because considering that we have JavaScript because of form validation, it really hadn't changed until very recently when HTML 5 introduced the constraint validation API. Hi, my name is Jeremy McPeak, and I invite you to spend some time with me as we use the constraint validation API to validate forms and provide a clean and seamless user experience. We'll start by taking a quick look at the built-in support for form validation in modern browsers. And then we'll dive right into the constraint validation API. And we'll design a flexible implementation that you can use just about anywhere. When we're done, you'll know how to write form validation code that you'll be able to use and reuse without having to touch the JavaScript again. So when you're ready, queue up the next video, and we will get started.