title: calling removeEventListener from within event listener?
body: <p>I have some simple code, but currently it does not remove the listener after the first call. How can I achieve this? Or do I really need to add redundant if/else checks on a var set upon notice? </p>
  
  <pre><code>    document.addEventListener("contextmenu", function(e){
          alert("Please remember this is someone's art! Give credit where it is deserved!");
          document.removeEventListener("contextmenu", function(e){
              console.log('User has been warned...');
          });
      }, false);
  </code></pre>
  
  <p><strong>Updated code</strong> Still same message every right click</p>
  
  <pre><code>    document.addEventListener("contextmenu", function msg(e){
          alert("Please remember this is someone's art! Give credit where it is deserved!");
          e.removeEventListener("contextmenu", msg, false);
      }, false);
  </code></pre>