// Attach an error event handler
  window.onerror = function( message ){
  
      // Create an <li> element to store our error message
      var li = document.createElement(“li”);
      li.innerHTML = message;
  
      // Find our error list (which has an ID of ‘errors’)
      var errors = document.getElementById(“errors”);
  
      // and add our error message to the top of the list
      errors.insertBefore( li, errors.firstChild );
  
  };