title: Why can't Web Worker call a function directly?
body: <p>We can use the web worker in HTML5 like this:</p>
  
  <pre><code>var worker = new Worker('worker.js');
  </code></pre>
  
  <p>but why can't we call a function like this?</p>
  
  <pre><code>var worker = new Worker(function(){
      //do something
  });
  </code></pre>