title: Javascript minification why is false replaced with !1 and true with !0
body: <p>I'm writing an app using Enyo2 which comes with a minification tool based on UglifyJS. 
  I've noticed that:</p>
  
  <pre><code>var t = false
  </code></pre>
  
  <p>is replaced with </p>
  
  <pre><code>var t=!1
  </code></pre>
  
  <p>The same way true is replaced with !0. I'm sure there is a good explanation for that, I just can't find it. Any idea?</p>