如何访问 angular 中动态创建的按钮？

Question

So, I am creating a quiz application where I have a scrollbar for questions and in that scrollbar I have buttons depending on the length of a question set. So I've created those buttons using *ngFor directive. Now what I want to do is whenever a user selects any option (mcq), the question buttons in the scrollbar should get highlighted in following way:

1. If user selects any option, then change the question button color to Green
2. If user skips the question, then change the question button color to Yellow

HTML Code for Question Scrollbar:

<div id="answer-buttons" class="ques-grid ">
            <button #navBarButton *ngFor="let item of items">{{item}}</button>
</div>

I'm have tried doing it by first accessing the buttons using ViewChild in ts file and then apply some logic, but it's not working, it is only changing the color of first button

@ViewChild('navBarButton',{ static: false }) navBarButton:ElementRef
//and in some function I've tried this logic
if(this.attemptedQuestionCount[this.currentQuestionIndex]==1){
  this.navBarButton.nativeElement.style.backgroundColor = "#228B22"
}
else{
  this.navBarButton.nativeElement.style.backgroundColor = "#FCF55F"
}

How can I achieve my objective?

Answer 1

You can check for attemptedQuestionCount and change background color like this

<div id="answer-buttons" class="ques-grid ">
<button *ngFor="let question of questions; let i=index"
    [style.background-color]="attemptedQuestionCount[i] === 1 ? '#228B22' : '#FCF55F'">{{question}}</button>
</div>

Answer 2

Add button tag as follows:

<button *ngFor="let question of questions; let i=index"
        [style.background-color]="attemptedQuestionCount[i] === 1 ? '#228B22' : '#FCF55F'">{{question}}</button>

Answer 3

You can add the click handler directly to the button using

<button *ngFor="let item of items; let indexOfelement=index" 
      (click)="heyYouClicked(indexOfelement)">{{item}}</button>

And then in the component you place the handler

export class AppComponent {
  items = ["hello", "world"]

  heyYouClicked(index){
    console.log("you clicked " + index)
  }
}

Answer 4

You can try ngClass<\/code> for simplicity.

<button #navBarButton *ngFor="let item of items" class="defualt_state" [ngClass]="{'new_state': (condition_here)}">{{item}}</button>