title: return !1 in javascript
body: <p>I have just come across a function in javascript which has <code>return !1</code></p>
  
  <p>I was just wondering what this actually meant?</p>
  
  <p>Why would you <code>return !1</code> or <code>return !0</code></p>
  
  <p>Could someone please explain what it means please?</p>
  
  <p>Here is the function that I came across:</p>
  
  <pre><code>function convertStringToBoolean(a) {
      typeof a == "string" &amp;&amp; (a = a.toLowerCase());
      switch (a) {
      case "1":
      case "true":
      case "yes":
      case "y":
      case 1:
      case !0:
          return !0;
      default:
          return !1
      }
  }
  </code></pre>
  
  <p>Thanks In advance!</p>