title: In Angular 5, insert value in reactive forms array at specific index
body: <p>Here, am using reactive forms array, i am unable to insert the <strong>QuestionType</strong> value into form array at specific index. Here is the JSON view of an array below:</p>
  
  <pre><code>{
    "SurveyName": "",
    "Questions": [
      {
        "QuestionName": "",
        "QuestionType": "",
        "AnswersList": [
          {
            "Answer": ""
          }
        ]
      }
    ]
  }
  </code></pre>
  
  <p>Here, is the inserting value in this way but, when am inserting like that key is removing from array here is the method below:</p>
  
  <pre><code>selectType(ID: number,event,index) {
      this.QuestionType = ID;
      this.SurveyForm.value.Questions[index].QuestionType = ID;
    }
  </code></pre>
  
  <p>It is the dynamic form to insert value at any index of an array so, please suggest me to solve this issue.</p>