title: tsconfig.json - Only build ts files from folder
body: <p>I am currently trying to build my ts files into a single ts files. The issue I'm getting is that my code below isn't doing what I thought it would. I used sourceRoot to attempt to set the only place it could get the source from but that didn't work. I have also tried putting a . infront of the directory but it still pulls from everywhere :(</p>
  
  <pre class="lang-js prettyprint-override"><code>{
     "compilerOptions": {
         "target": "ES5",
         "noImplicitAny": true,
         "removeComments": true,
         "preserveConstEnums": true,
         "out": "www/js/app.js",
         "sourceMap": true,
         "sourceRoot": "www/app"
     }
  }
  </code></pre>
  
  <p>all files including those not inside of www/app build :(</p>
  
  <p>for now I've moved back to manually specifying the files:</p>
  
  <pre class="lang-js prettyprint-override"><code>{
      "compilerOptions": {
          "target": "ES5",
          "noImplicitAny": true,
          "removeComments": true,
          "preserveConstEnums": true,
          "out": "www/js/app.js",
          "sourceMap": true
      },
      "files": [
          "./www/app/app.ts",
          "./www/app/menu/menuController.ts",
          "./www/app/playlists/playlistsController.ts"
      ]
  }
  </code></pre>
  
  <p>is it possible to restrict the source directories to be only www/app?</p>
  
  <p>Thanks</p>