Now we need a module to enable users to join the new network, and that’s Example 20-5, rnsignup.php. This is a slightly longer program, but you’ve seen all its parts before.
Let’s start by looking at the end block of HTML. This is a simple
form that allows a username and password to be entered. But note the use
of the empty
span given the
'info'. This will be the destination of the
Ajax call in this program that checks whether a desired username is
available. See Chapter 18 for a complete description
of how this works.
Now go back to the program start and you’ll see a block of
onBlur event when focus is removed
from the username field of the form. First it sets the contents of the
span I mentioned (with the
'info') to an empty string, which clears it
in case it previously had a value.
Next a request is made to the program rnchecker.php, which reports whether the
username user is available. The returned result
of the Ajax call, a friendly message, is then placed in the
recognize from the Chapter 17 section of form
validation. This section also uses the
sanitizeString function to remove
potentially malicious characters before looking up the username in the
database and, if it’s not already taken, inserting the new username
$user and password
Upon successfully signing ...