There may be a better way to do this, but: When writing JS I often make a silly little typo or something that I don't notice unless I: - notice that something seems broken - open Chrome's developer toolbar, which I inevitably closed last time to get

Growl-like popup on JS error.js

 
-if RAILS_ENV == 'development'
  :javascript
    $(function() {
      var notify = function(icon, title, body) {
        if (window.webkitNotifications.checkPermission() == 0) {
          var popup = window.webkitNotifications.createNotification(
            icon, title, body);
          popup.show();
          return true;
        }
      }

      //Bind the popup to window.onerror
      window.onerror = function(str, url, line) {
        notify("", "JS Error", str+'\n'+url+':'+line);
      };
    });