JSON - Response As An Array

When you hope your json response as an array, not as an object, so do it like this one:
Server:

    $data = array();

    $data[] = 'lady gaga';

    $data[] = 'luna maya';

    $data[] = 'barack obama';

    echo json_encode($data);

Client:

    $data = eval('('+ajax.responseText+')');

    for(i=0; i<data.length; i++){

        element.innerHTML = innerHTML + data[i];

    }

JSON - Response As An Array