为什么我的角分量法不起作用?

当this.correct/this.incorrect设置为null/false时,h2正确/错误消息不会隐藏自身。

这是HTML模板中应该切换的部分,但它们不是。

  <h2 *ngIf="correct">Correct</h2>
  <h2 *ngIf="incorrect">Incorrect! The answer is {{ questions[counter].answer }}</h2>

compareAnswer(userAnswer) {

  const currentAnswer = this.questions[this.counter].answer;
  if (currentAnswer.includes(userAnswer.answer)) {
    console.log('Correct!');
    this.correctAnswers += 1;
    this.correct = true;
  } else {
    this.incorrect = true;
  }
  //the correct/incorrect h2s show and then this method should clear for the 
  //next question
  setTimeout(this.handleNextQuestion, 2000);
}

handleNextQuestion() {
  //setting these properties should connect with the ngIf on the h2's and 
  //hide them, but its not doing that.
  this.correct = null;
  this.incorrect = null;

  this.counter += 1;
}

组件属性正确/不正确在组件上,如下所示:

  correct = null;
  incorrect = null;