implementing php & jquery for form validation

I have a live preview form: http://davidwalsh.name/jquery-comment-preview Which uses jquery to display the preview in real time:

$(document).ready(function() {
  $('#live-preview-form input, #live-preview-form textarea').bind('blur keyup',function() {
    $('#lp-comment').text($('#comment').val());
    $('#lp-comment').h开发者_运维百科tml($('#lp-comment').html().replace(/\n/g,'<br />'));
  });
});

what if i need to apply some PHP function on "#comment" which comes from textarea, before putting it in the jquery validate?

If you want to apply PHP functions, you must use jquery ajax(POST the value to a php page and get the returned result).

For example:

process.php:

<?php
function my_function($in){
    ....
    return $out;
}

$result = my_function($_POST['q']);
echo json_encode($result);
?>

js:

$(document).ready(function() {
  $('#live-preview-form input, #live-preview-form textarea').bind('blur keyup',function() {

    $.ajax({type: "POST", url: "function.php", data:{ "q": $('#comment').val()}, dataType: "json", 
      success: function(result){
        $('#lp-comment').text(result);
        $('#lp-comment').html($('#lp-comment').html().replace(/\n/g,'<br />'));
      }});
  });
});

However, this is not recommended because users query your server every time when they type a single character. The best way is to by a javascript function instead of a PHP function.

I think you should use the jquery form validation plugin available here. It deals with all the basic form validation you need .