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++; } }

当我运行此代码时，它说它无法将“getQuestionIndex”设置为未定义。 但是Ique不是将它设置为0吗？ 我在 Quiz 构造函数中将 this.questionIndex 设置为 0。 我在这里想念什么？

Answer 1

const quiz = 新测验（问题）； 应该是 const quiz = new Quiz (questions);