How to pass a Javascript string to php on the same page

By the time your browser renders the page, PHP has finished its job and closed the connection.

To pass some value determined on the client-side with js you need a new request. This means you need to use Ajax.

PHP parses data server-side (before the page loads), whereas JavaScript handles everything browser-side (after or on page load). You can't pass JavaScript into PHP functionality unless you use AJAX to send the PHP script a variable:

JavaScript

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js">

<script type="text/javascript">
   // Find whatever string you need
   var something = $('.input').val();

   $(function() {
      $.ajax({
         url: '/path/to/php_script.php',
         type: 'POST',
         data: 'variable='+something,
         success: function(data) {
            $('.display_div').html(data);
         }
      });
   });

</script>

PHP

$something = $_POST['variable'];

// Do something with it
echo strlen($something);

You'll need to make a request to the server via JavaScript, since PHP is a server-side language. You could use a POST or GET variable to send the string to the same page and then add PHP code to check for that variable when the page is loaded.

The PHP would be something like:

if(isset($_POST['string'])) {
// do something with the string
}