title: Where and how does React Native resolve .android.js and .ios.js files?
body: <p>The React Native packager has a feature where it automatically chooses between <code>*.android.js</code> and <code>*.ios.js</code> files depending on the environment being built for. I'd like to see if the same mechanism can be used for <code>*.web.js</code> files as well, allowing a web application to be built in the same repository as well. </p>
  
  <p>I'm trying to figure out how this works and where in the code it's implemented, but I can't seem to find it. Is there a way to just set an ENV variable to <code>web</code> and have it work? </p>