title: alert when user attempts to enter key into textbox
body: <p>So I've been searching for a bit now for code that will alert a user with a message (I know how to do an alert) when they try to enter any sort of text into a blank textbox.</p>
  
  <p>Here is my code.  What do I add to cause the <code>sendMsg()</code> function to be called?</p>
  
  <pre><code>&lt;script&gt;
    function sendMsg()
    {
      alert ("change msg content here");
    }
  &lt;/script&gt;
  </code></pre>
  
  <p>here is the HTML:</p>
  
  <pre><code>&lt;body&gt;
    &lt;input type="text" name=""&gt;
  &lt;/body&gt;
  </code></pre>