versions.js

// option 1 - "versions" key points to an array
{"versions":
  [
    {"version":{"id":...}},
    {"version":{"id":...}},
  ]
}

// option 2 - "version" key points to an array
{"versions":
  {
    "version":
      [{"id":...}]
      [{"id":...}]
  }
}

// option 3 - "versions" key points to an array
{"versions":
  [
    {"id":...},
    {"id":...}
  ]
}

// option 4 - "versions" key points to a hash
{"versions":
  {
    "version_123":{"id":...},
    "version_234":{"id":...},
    "version_345":{"id":...}
  }
}

versions.php

<?php

// option 3, in PHP format - 'versions' key points to an array of arrays
$versions = array(
  array('id' => 1, /*...*/),
  array('id' => 2, /*...*/),
);