我想改变按钮的颜色点击按钮。
我正在创建测验应用程序。
点击按钮后，如果答案正确，颜色应更改为绿色，如果答案错误，应更改为红色。
成功了我已经成功了
但现在的问题是，如果答案是错误的，那么它的颜色改变为红色，正确答案按钮的颜色改变为绿色。
如何做到这一点？

play-quiz.html

<ion-list>
    <ion-row class="marginTop">
      <ion-col class="border ion-text-center">
        Grand Central Terminal, Park Avenue, New York is the world's
      </ion-col>
    </ion-row>

    <ion-row class="marginTop">
      <ion-col class="ion-text-center">
        <ion-button id="1" #first class="btn" expand="block" (click)="onClick(first,'1')">
          Largest Railway Station
        </ion-button>
      </ion-col>
    </ion-row>

    <ion-row>
      <ion-col class="ion-text-center">
        <ion-button id="2" #second class="btn" expand="block" (click)="onClick(second,'2')">
          highest railway station
        </ion-button>
      </ion-col>
    </ion-row>

    <ion-row>
      <ion-col class="ion-text-center">
        <ion-button id="3" #third class="btn" expand="block" (click)="onClick(third,'3')">
          longest railway station
        </ion-button>
      </ion-col>
    </ion-row>

    <ion-row>
      <ion-col class="ion-text-center">
        <ion-button id="4" #four class="btn" expand="block" (click)="onClick(four,'4')">
          None of the above
        </ion-button>
      </ion-col>
    </ion-row>

    <ion-row>
      <ion-col>
        <ion-button class="btn right" expand="small">
          Next
        </ion-button>
      </ion-col>
    </ion-row>

  </ion-list>

play-quiz.ts。

answer: any = "1";

onClick(ionicButton, btn: any) {
      if(this.answer == btn){
        ionicButton.color =  'success';
      } else {
        ionicButton.color =  'danger';
      }
  }