[рони]

Diana123456,
тоже самое чуть покороче

$("#buttonSort").click(function() {
    function d(a) {
        return (new Date(a)).getTime()
    }
    var e = $(":checked").index("[name='sort']"),
        c = [{key: "name"}, {key: "lastname"}, {key: "dateofstart",foo: d}, {key: "dateofend",foo: d}][-1 < e ? e : 0];
    dataObj.items.sort(function(a, b) {
        a = a[c.key];
        b = b[c.key];
        c.foo && (a = c.foo(a), b = c.foo(b));
        return a < b ? -1 : a > b ? 1 : 0
    });
    $(".entered_data").html("");
    testProject.render()
});