title: Using "let" in javascript in terms of browser compatibility?
body: <p>What are the options for using the <code>let</code> keyword in javascript. It seems like it would be really useful.</p>
  
  <p>I've seen <a href="http://traceur-compiler.googlecode.com/git/demo/repl.html" rel="noreferrer">traceur</a>, but I'm wondering if there are any other options, so I don't have to run entire projects through it.</p>
  
  <p>Is it even possible with some type of polyfill or library. Or do I basically have to wait until all the old browsers die out to use it natively...</p>