Q:

two ajax request url (success/fail)

Good day,
I was in some disarray . I have a ajax request from select2. Also I have two urls. How should I event organized If / else success/failure statements, if suddenly one will not work , then send an inquiry to another link?
I'm trying again and again and alwas there is error somewhere((
$(".js-data-example-ajax").select2({
    language: "ru",
    placeholder: "Serach.........",
    disabled: false,
    selected: true,
    ajax: {
        url: "url_1",
        dataType: 'json',
        delay: 250,
        data: function (params) {
            return {
                q: params.term + "%", // search term
            };
        },
        processResults: function (data) {
            if (data.features.length > 0) {
                var resultArray = [];
                $.each(data.features, function (index, value) {
                    value.attributes.id = value.attributes.OBJECT_ID;
                    resultArray.push(value.attributes);
                });
                return {
                    results: resultArray
                };
            } else {
                return []
            };
        },
        cache: true
    },
    escapeMarkup: function (markup) { return markup; }, // let our custom formatter work
    minimumInputLength: 5,
    templateResult: formatRepo, // omitted for brevity, see the source of this page
    templateSelection: formatRepoSelection // omitted for brevity, see the source of this page

});

A:

It should be quite simple because you only have to call the first url and, on error, call the second.
$.ajax(function(data){
            url: "url_1",
            ...,
            success(function(data){
                //do stuff on success
            }),
            error(function(e){
                $.ajax(function(data{
                    //call the second url
                })
            })
        })

