我的JSON数组如何被格式化以迭代这个$ .each？

Question

I need to iterate through data that get via JSON with this code:

setInterval(function() {

        console.log("running");
        $.ajax({
            type     : 'get',
            url      : 'data.txt',
            dataType : 'json',
            success  : function(response) {

                console.log(response.bookings) // returns undefined

                $.each(response.bookings, function(index, booking) {
                    sc.status(booking.seat_id, 'unavailable');

                    console.log(booking.seat_id); // returns nothing

                });
            }
        });
    }, 3000); //every 3 seconds

The data is currently formatted like this:

[{
  "bookings": [
    {
      "seat_id": "1_4"
    },
    {
      "seat_id": "4_2"
    }]
}]

But that doesn't seem to be working. What is the correct format that I need to use? I tried a ton of options but can't get it working.

UPDATE:

The error I now get in the console is:

jquery-1.11.0.min.js:2 Uncaught TypeError: Cannot read property 'length' of undefined
    at Function.each (jquery-1.11.0.min.js:2)
    at Object.success ((index):145)
    at j (jquery-1.11.0.min.js:2)
    at Object.fireWith [as resolveWith] (jquery-1.11.0.min.js:2)
    at x (jquery-1.11.0.min.js:4)
    at XMLHttpRequest.b (jquery-1.11.0.min.js:4)

and line 145 is:

$.each(response.bookings, function(index, booking) {

Answer 1

I finally found the solution. Thank you to everyone who helped. It's pretty simple and stupid. I only had to change the JSON response from:

[{
  "bookings": [
    {
      "seat_id": "1_4"
    },
    {
      "seat_id": "4_2"
    }]
}]

to

{
  "bookings": [
    {
      "seat_id": "1_4"
    },
    {
      "seat_id": "4_2"
    }]
}

Basically get rid of the []