单选按钮绑定：Angular 5

Question

此代码基本上用于 MCQ，其中 4 options.I 试图在每次用户使用单选按钮选择并提交正确答案时增加计数器 (var) button.But 单选按钮绑定不是'以某种方式无法正常工作。尝试在 Whosebug 上进行谷歌搜索，但提供的解决方案还不够。

HTML:

div *ngFor="let abc of questArrayNew1 ;let j = index" >

           {{j+1}}.{{abc.OP[j]}}

          <br>
        <input type="radio" name="s" [(ngModel)]="hello" [value]="abc.OP[j+1]" >{{abc.OP[j+1]}}

        <br>  
        <input type="radio" name="s" [(ngModel)]="hello" [value]="abc.OP[j+2 ]">{{abc.OP[j+2]}}

        <br>
        <input type="radio" name="s" [(ngModel)]="hello" [value]="abc.OP[j+3]">{{abc.OP[j+3]}}

        <br>
      <input type="radio" name="s" [(ngModel)]="hello" [value]="abc.OP[j+4]">{{abc.OP[j+4]}}

        <br>

          </div>'
<div>
    <button type="submit" class="btn btn-light" id="button1" (click)="submitAns(radio)">Submit</button>
</div>

.TS:

 submitAns(hello:string)
  {

  {
     if (hello == this.questArrayNew1[1]) //Checking if ans is right

    {
      console.log(hello); //undefined is being returned
      console.log(this.questArrayNew1); //this is returning perfect array
      this.counter++;

    }
    else
    { 

      console.log("Wrong answer");
    };

  } 

}

JSON:

[  
  {


    "OP":["The Government of India (GoI) has launched the web-based application e-FRRO scheme for foreigners. What does ‘FRRO’ stands for ?",
    "Foreigners Regional Registration Office" , 
    "Foreigners Registry Registration Office", 
    "Foreigners Reacceptance Registration Office", 
    "Foreigners Regaining Registration Office" ]

},

  {


        "OP":["QUES2","ADASD" , "ASDAD", "ASDASD", "ASDADS"]

    }


]

Answer 1

已修复：

<div>
    <button type="submit" class="btn btn-light" id="button1" (click)="submitAns(hello)">Submit</button>
</div>

单选按钮绑定：Angular 5

Radio Button binding : Angular 5

html

angularjs-directive

angular