Question

Can someone explain in an easy way how to make jQuery send actual JSON instead of a query string?

$.ajax({
    url      : url,
    dataType : 'json', // I was pretty sure this would do the trick
    data     : data,
    type     : 'POST',
    complete : callback // etc
});

This will in fact convert your carefully prepared JSON to a query string. One of the annoying things is that any array: [] in your object will be converted to array[]: [], probably because of limitations of the query sting.

Answer 1

You need to use JSON.stringify to first serialize your object to JSON, and then specify the contentType so your server understands it’s JSON. This should do the trick:

$.ajax({
    url: url,
    type: "POST",
    data: JSON.stringify(data),
    contentType: "application/json",
    complete: callback
});

Note that the JSON object is natively available in browsers that support JavaScript 1.7 / ECMAScript 5 or later. If you need legacy support you can use json2.