title: document.onkeypress is not working, how to fix?
body: <p>Is there any reason the following code should not return anything in my console log?!</p>
  
  <pre><code>document.onkeypress =  zx();
  
  function zx(){
      console.log(event.keyCode);
  } // zx
  </code></pre>
  
  <p><code>window.onkeypress</code> also doesn't work.</p>
  
  <p>Other attempts has been made, like these:</p>
  
  <pre><code>document.onkeypress =  zx(event);
  
  function zx(event){
      console.log(event.keyCode);
  } // zx
  </code></pre>
  
  <p>-</p>
  
  <pre><code>document.onkeypress =  zx;
  
  function zx(){
      console.log(event.keyCode);
  } // zx
  </code></pre>
  
  <p>Thanks!</p>