使用Ajax加载数据以使用Tribute.js进行提及

Question

您好，我正在尝试使用tribute.js加载数据。但是，我遇到了一个错误Unable to append to values, as it is a function。目前，我的配置是：

$(document).ready(function () {


    var tribute = new Tribute({
        values: function (search, cb) {
            getUsernames(search, users => cb(users))
        },
        menuItemTemplate: function (item) {
            return '<img src="'+item.original.img.url + '">' + item.original.name + " " + item.original.last;
        },
        selectTemplate: function (item) {
            return '@' + item.original.username;
        },
    });
    tribute.attach(document.getElementById("id_content"));

    function getUsernames(search, cb){
        var xhr = new XMLHttpRequest();
        xhr.open('GET', '/get/user/mentions?q='+search, true);
        xhr.setRequestHeader('Content-Type', 'application/json');
        xhr.onload = function () {
            var data = JSON.parse(xhr.responseText);
            cb(data);
            if (xhr.readyState == 4 && xhr.status == "200") {
                $.each(data, function(i, item) {
                    tribute.append(0,[
                        {
                            name: item.first_name,
                            last: item.last_name,
                            username:item.username,
                            img: item.image
                        },
                    ]);
                });
            } else if (xhr.status === 403) {
                cb([]);
            }
        }
        xhr.send(null);
    }

})

是each循环的原因，我想知道如何正确地从Ajax加载数据？