Mastering Bootstrap 4

Form validation

Although this book does not cover the server-side logic required to make this happen, we will need to implement one last essential stepping stone, client-side form validation. In other words, what is currently missing from our form, aside from the server-side code to send or store the actual message, is a way for us to validate the user's form input and to notify the user should they fill out the form incorrectly. One obvious solution is to identify what type of input the form fields require, and then to use either plain JavaScript or jQuery to check the contents of each field using regular expressions. Once an expression fails to match, we could then set the contents of a specific HTML element to contain an error message. However, ...