title: How to handle click event in javascript?
body: <p>Today is my first day at a new job (a Front End Lead on a large website.)  One of my tasks is to implement a button that fires an event when it's clicked.  I had no clue, so after googling a bit, I came up with this:</p>
  
  <pre><code>&lt;html&gt;
  &lt;head&gt;
  &lt;script type="text/javascript"&gt;
  function popup(); 
  {
      alert("Hello World") ==&gt; alert("Hello World");
  }
  &lt;/script&gt;
  &lt;/head&gt;
  &lt;body&gt;
  
  &lt;input type="button" value="Click Me!" onclick="popup()"&gt;&lt;/input&gt;&lt;br&gt;&lt;/br&gt;
  
  &lt;/html&gt;    
  &lt;/body&gt;
  </code></pre>
  
  <p>The problem is, when I click my button, nothing happens.</p>
  
  <p><strong>EDIT</strong> Updated based on MICHEL's comments</p>