How can I call PHP functions by JavaScript?

How can I call PHP functions by JavaScript?

Yes, you can do ajax request to server with your data in request parameters, like this (very simple):

Note that the following code uses jQuery

jQuery.ajax({
    type: POST,
    url: your_functions_address.php,
    dataType: json,
    data: {functionname: add, arguments: [1, 2]},

    success: function (obj, textstatus) {
                  if( !(error in obj) ) {
                      yourVariable = obj.result;
                  }
                  else {
                      console.log(obj.error);
                  }
            }
});

and your_functions_address.php like this:

    <?php
    header(Content-Type: application/json);

    $aResult = array();

    if( !isset($_POST[functionname]) ) { $aResult[error] = No function name!; }

    if( !isset($_POST[arguments]) ) { $aResult[error] = No function arguments!; }

    if( !isset($aResult[error]) ) {

        switch($_POST[functionname]) {
            case add:
               if( !is_array($_POST[arguments]) || (count($_POST[arguments]) < 2) ) {
                   $aResult[error] = Error in arguments!;
               }
               else {
                   $aResult[result] = add(floatval($_POST[arguments][0]), floatval($_POST[arguments][1]));
               }
               break;

            default:
               $aResult[error] = Not found function .$_POST[functionname].!;
               break;
        }

    }

    echo json_encode($aResult);

?>

Try This

<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>

How can I call PHP functions by JavaScript?

use document.write
for example,

<script>
  document.write( <?php add(1,2); ?> );
  document.write( <?php milt(1,2); ?> );
  document.write( <?php divide(1,2); ?> );
</script>