title: Casting document.getElementById to access files in TypeScript
body: <p>I am very new to angularjs. I wasn't able to find the solution online. 
  I would like to read the text from a file. I was trying to follow this example. 
  <a href="https://stackoverflow.com/questions/26165919/filereader-not-loading-file-properly-using-angularjs">FileReader not loading file properly using AngularJS</a></p>
  
  <p>However, since I'm using TypeScript, I receive this error for this line</p>
  
  <pre><code>document.getElementById('fileInput').files[0];
  </code></pre>
  
  <p>Error:
  Property 'files' does not exist on type 'HTMLElement'.</p>
  
  <p>Please suggest me how I can cast to use the files. </p>