Now we need a module to enable users to join the new network: that’s Example 21-5, signup.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 17 for a complete description of how this
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 checkuser.php, which reports whether the
user is available. The
returned result of the Ajax call, a friendly message, is then placed in
recognize from the discussion of form validation in Chapter 16. This section also
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
$user and password
Upon successfully ...