javascript and php validation? - php

Question

I have some javascript and php code written to validate a field. Both codes are to validate whether the field is not empty, is within a limit of 35 characters and contains only alphabetic characters and a hyphen(-). What i want to do is for both the javascript and php to validate simultaneously and show they're messages for entering incorrect data but it only seems that the javascript is validating properly due to the fact that an alert pops up but no message is shown from the php side. Here is my code :
<script type="text/javascript">
function validateFamily()
{
var family=document.getElementById('family');
var stringf = document.getElementById('family').value;
var ck_password = /^[A-Za-z-]/;
if (family.value=="")
{
alert("Family name must be filled out");
return false;
}
else if (document.getElementById('family').value.length > 35)
{
alert("Family name cannot be more than 35 characters");
return false;
}
else if(!ck_password.test(stringf))
{
alert("Family name can only contain alphabetic characters and hypehns(-)");
return false;
}
return true;
}
</script>
<?php
if (isset($_POST['submit'])) {
$flagf = false;
$badcharf = "";
$stringf = $_POST["family"];
$stringf = trim($stringf);
$lengthf = strlen($stringf);
$strmsgf = "";
if ($lengthf == 0) {
$strmsgf = '<span class="error"> Please enter family name</span>';
$flagf = true;}
else if ($lengthf > 35) {
$strmsgf = '<span class="error"> Can not enter more than 35 characters</span>';
$flagf = true;}
else {
for ($if=0; $if<$lengthf;$if++){
$cf = strtolower(substr($stringf, $if, 1));
if (strpos("abcdefghijklmnopqrstuvwxyz-", $cf) === false){
$badcharf .=$cf;
$flagf = true;
}
}
if ($flagf) {
$strmsgf = '<span class="error"> The field contained the following invalid characters: '.$badcharf.'</span>';}
}
if (!$flagf) {
$strmsgf = '<span class="error"> Correct!</span>';}
}
?>
<form name="eoiform" method="POST" action="<?php echo $_SERVER["PHP_SELF"];?>" id="eoi" onsubmit="return validateFamily() && validateGiven() && validateMaleFemale() && validDate() && validateAddress() && validatePost() && validateParent() && validateWork() && validateHome() && validateMob() && validateCheckBoxes() && validateTextBoxes();">
<b>Student's Family Name</b>
<br>
<input type="text" id="family" name="family" /><?php echo $strmsgf; ?>
<input type="submit" name="submit" id="submit" value="submit" />
</form>
Could anyone help me with this?

Answer 1

Your JavaScript and PHP cannot execute simultaneously because the former happens in the user's browser before the form is POSTed and the latter happens after this once the form has reached the server.
You can verify this by inspecting the source code of your webpage in the browser: there's no PHP!
If your JavaScript makes the catch, nothing is sent to the server because you return false. In practice it makes sense to have the server-side checks in place in case:
Someone is tricky and modifies the form after it's validated but before it's sent.
JavaScript is disabled or breaks for some reason.

Answer 2

The way this form works is that you have a JS function in the form's onsubmit property which can prevent the form's submission if a value is wrong. If your JS function returns false because of an error, the form will never be submitted.
In order to get the functionality you want, you need to perform the checks on the server side only, but you'll need to submit the form each time for that to occur...
An alternative way would be to check the entered values when the user finishes adding a value to each of your text fields, i.e. attach a JS function to the fields' blur() property, and make an AJAX call to your server that will validate the field contents before the form is actually submitted.
You can use jQuery's validate plugin for more complex validations, if these can be done on the client side, as well:
http://jqueryvalidation.org/

Answer 3

As paislee stated there is no way you can simultaneously run php and javascript. There are however dynamic requests you can send to run some php code and it's called AJAX. This will also not ensure an absolutely accurate simultaneous execution but will be closer to what you aim for.