AngularJs - 在ng-init上隐藏

Question

我正在使用ng-init指令进行初始化。我有一个按钮（btnPrevious），它不应该在启动时显示，而只能在ng-click调用时显示。如何在隐藏按钮的情况下初始化应用程序，然后在ng-click上显示？

var MyApp = angular.module('MyApp', ['angular-loading-bar']);

MyApp.controller('MyController', function ($scope, $http, $rootScope) {

    $scope.getFirstQuestion = function () {
        $http.get('/URL')
            .success(function (qst) {
                $scope.question = qst;
            })
            .error(function (error) {
                $scope.status = error.message;
                console.log($scope.status);
            });
    }
        
    $scope.getNextQuestion = function (p, r) {
        
        //
    }

    $scope.getPreviousQuestion = function () {

        //
    }
});

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="MyApp" class="container">
    <div ng-controller="MyController" ng-init="getFirstQuestion()">
        <h3>{{question.Description}}</h3>
        <ul>
            <li ng-repeat="r in question.Answers">
                <input type="button" id="{{r.Id}}" value="{{r.Description}}"
                       ng-click='getNextQuestion(question.Id, r.Id)' class="btn btn-default" />
            </li>
        </ul>
        <input type="button" ng-click='getPreviousQuestion()' name="btnPrevious" value="Previous" class="btn btn-default" />
    </div>
</div>