11.2. Validating Forms

11.2.1. Problem

Most registration forms require input of email address, a password (two times), a username, and some other information, like a birth date. This applies to email services, web shops, or forums.

It’s easy to imagine John Doe, who wants to buy a new monitor at some web shop where the registration also requires the input of a captcha (a barely legible group of random characters to tell the difference between a human and a bot). He fills out the complete form, which takes some time, and then submits the form. After about five seconds, the form is displayed again, with some error message at the top: he forgot to fill out the street field. He fixes that and submits again. Another five seconds pass: now he missed the password and captcha field! Huh? He did fill those in, but he had to fill them in again after the failed first attempt.