[devote]

$out = array(
  "x" => 1,
  "ig" => 234,
);
echo json_encode( $out );

JS:

$.ajax({
    url: "ajax.php",
    data: { n: 1 },
    type: "post",
    dataType: "json",
    success: function( data, textStatus, xhr ) {
        alert( data.x );
        alert( data.ig );
    }
});