为什么我收到“无法设置未定义的属性”的错误？

Question

 const quiz = new quiz(questions); populate(); function Question(text, choices, answer){ this.text = text; this.choices = choices; this.answer = answer; } Question.prototype.correctAnswer = function(choices){ return choice === this.answer; } function Quiz(questions){ this.score = 0; this.questions = questions; this.questionIndex = 0; } quiz.prototype.getQuestionIndex = function(){ return this.questions[this.questionIndex]; } quiz.prototype.isEnded = function(){ return this.questions.length === this.questionIndex; } quiz.protype.guess = function(answer){ this.questionIndex++; if(this.getQuestionIndex().correctAnswer(answer)){ this.score++; } }

When I run this code, it says it cannot set 'getQuestionIndex' to undefined. But didn't Ique set it to 0? I set this.questionIndex to 0 in my Quiz constructor. What am I missing here?

Answer 1

const quiz = new quiz(questions); should be const quiz = new Quiz (questions);