问如何(最好)在作为回调传递的对象方法中访问“this”

EN

function Prompter() {

    this.getUserName = function (callback) {

        var schema = {
            properties: {
                name: {
                    description: "Tu nombre por favor:",
                    pattern: /^[ñÑa-zA-Z\s\-]+$/,
                    message: 'Solo letras, por favor',
                    required: true
                }
            }
        };
        prompt.get(schema, callback);
    };
}

function Game() {

    this.qGenerator = null;
    this.prompter = null;
    this.user = "";

    this.doNextRound = function () {
       //// omitted for brevity
    };

    this.init = function () {
        this.qGenerator = new QuestionGenerator();
        this.prompter = new Prompter();
    };

    this.startGame = function () {
        this.prompter.getUserName(this.storeUserName);
    };

    this.storeUserName = function (err, result) {
        if (err) {
            this.handleErr(err);
            return;
        }
        this.user = result.name;
        this.doNextRound();
    };
}

const game = new Game();
game.init();
game.startGame();

this.doNextRound

TypeError: this.doNextRound is not a function