Pass arrays as parameters with jQuery AJAX?

You will probably need to name your variable as "parameter3[]" for PHP's sake:

$.get('/controller/method/',
  {
    "parameter1": "value1",
    "parameter2": "value2",
    "parameter3[]": ["a","b","c"]
  },
  function(data) {
    if (data) {
    }
  else {
  }
});

$_GET["parameter3"] will appear in PHP as

Array
(
    [0] => "a"
    [1] => "b"
    [2] => "c"
)