title: Operator '==' cannot be applied to types string and number
body: <p>How to check the value of a number?</p>
  
  <pre><code>for(var index in this.choicesDM) {
    if(index == 0) {
      this.currentChoice = this.choicesDM[index]
    }
  }
  </code></pre>
  
  <p>Here I get the <strong>error as mentioned</strong> in the <strong>title</strong> of the question. I also tried to explicitly define the type of index. But didn't work.
  Found this <a href="https://stackoverflow.com/a/39243442/2904573">link</a> but didn't got the solution.</p>