addEvent(window, "load", validator.init);

A simple PHP form using regular expressions for validation

function field($name, $text) {
global $ERRORS;
echo "

if (array_key_exists($name,$ERRORS)) {
echo " class=\"error\"";
}
echo ">$text\n";
echo "\n";
if (array_key_exists($name,$ERRORS)) {
$err = $ERRORS[$name];
echo "$err";
} else {
echo "";
}
echo "

\n";
}
CHAPTER 7 n FORM VALIDATION AND JAVASCRIPT 155
field("firstname", "First name");
field("lastname", "Last name");
field("heads", "Number of heads");
field("dob", "Date of birth (DD/MM/YYYY)");
field("email", "Email address of someone you don't like for spamming purposes");
?>

And there you have it: form validation with regular expressions, progressively enhanced
to use DOM scripting.
Now that there??™s an infrastructure in place to do the validation of this form, there are
numerous ways to add extra enhancements. Here I??™ll discuss two: having the page add the
error span itself (instead of requiring it to already be present in the HTML) and preventing
the form being submitted if there are errors.
Adding the Error Span from JavaScript
In Listing 7-2, the PHP server code writes out a for each field,
even when there aren??™t any errors, as a placeholder for the error message.


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