How to post an empty array (of ints) (jQuery -> MVC 3)

You could do this:

var myIntArray = new Array();

// add elements or leave empty
myIntArray.push(1);
myIntArray.push(5);

var data = myIntArray.length > 0 ? { myIntArray: myIntArray } : null;

$.ajax({
    url: '@Url.Action("someAction")',
    type: 'POST',
    data: data,
    traditional: true,
    success: function (result) {
        console.log(result);
    }
});

or use a JSON request:

var myIntArray = new Array();
// add elements or leave empty
myIntArray.push(1);
myIntArray.push(5);

$.ajax({
    url: '@Url.Action("someAction")',
    type: 'POST',
    data: JSON.stringify(myIntArray),
    contentType: 'application/json',
    success: function (result) {
        console.log(result);
    }
});