title: What is the difference between using : and => for the return type with a TypeScript function?
body: <p>I have the following code:</p>
  
  <pre><code>///&lt;reference path="../typescript/jquery.d.ts" /&gt;
  function addThemePrototypes() {
      var templateSetup = new Array();
      $.fn.addTemplateSetup = function(func, prioritary)
      {
          if (prioritary)
          {
              templateSetup.unshift(func);
          }
          else
          {
              templateSetup.push(func);
          }
      };
  }
  </code></pre>
  
  <p>Can someone tell me why this should be declared with => void ?</p>
  
  <pre><code>interface JQuery {
      addTemplateSetup: (func: Function, priority: bool) =&gt;void;
  }
  </code></pre>
  
  <p>I guess I am a bit confused about how to do the returntype from a javascript function. Sometimes I 
  see : jQuery and now I am seing => void. What is the difference between the two?</p>