boolean variables posted through AJAX being treated as strings in server side

Also you can use filter_var function with filter FILTER_VALIDATE_BOOLEAN. According to php documentation it

Returns TRUE for "1", "true", "on" and "yes". Returns FALSE otherwise. If FILTER_NULL_ON_FAILURE is set, FALSE is returned only for "0", "false", "off", "no", and "", and NULL is returned for all non-boolean values.

So receiving of POST parameter will look like:

$isClass = filter_var ($_POST['isClass'], FILTER_VALIDATE_BOOLEAN);

You aren't doing anything wrong per se, it's just that when it gets posted, it looks like this:

operation=add_cart&isClass=true&itemId=1234

PHP can't tell what the data type is because it isn't passed, it's always just a string of POST data, so compare it to "true" to do your checks, like this:

if($_POST['isClass'] === "true"){  //Code to add class to session cart}else{  //Code to add pack to session cart}

This is a bit of an old question, but I'm surprised nobody has posted this here as solution.

Just use 1 and 0 instead of true and false when you're constructing your ajax requests.When you do a == comparison, they'll be interpreted as true/false.

JS:

$.ajax({  url: '....',  data: {    foo: 1,    bar: 0  }});

PHP:

<?php  if ($_GET['foo']) {     //...  } else {     //...  }  echo $_GET['bar'] ? 'bar is true' : 'bar is false';?>