run php from javascript function code example

Example 1: call php function in js

<script>
  var phpadd= <?php echo add(1,2);?> //call the php add function
  var phpmult= <?php echo mult(1,2);?> //call the php mult function
  var phpdivide= <?php echo divide(1,2);?> //call the php divide function
</script>

Example 2: how to run php inside js

You can't run PHP with javascript. JavaScript is a client 
side technology (runs in the users browser) and PHP is a 
server side technology (run on the server). If you want to 
do this you have to make an ajax request to a PHP script and 
have that return the results you are looking for.