Random parameters in javascript
<p>I know this may be a very basic question, sorry if it is but in javascript/jquery i sometimes come into contact with a function having a random parameter that doesn't seem to serve an obvious purpose, such as this one below used on the jquery website.</p>

<pre><code>    $("div").mousemove(function(e){  
      var pageCoords = "( " + e.pageX + ", " + e.pageY + " )";  
      var clientCoords = "( " + e.clientX + ", " + e.clientY + " )";  
      $("span:first").text("( e.pageX, e.pageY ) : " + pageCoords);  
      $("span:last").text("( e.clientX, e.clientY ) : " + clientCoords);  
    });  
</code></pre>

<p>Here the function has a parameter of e, i don't get why though i know if it didn't have an e it could also work because that's how i tend to use javascript. Why would a programmer do this?  </p>
