add custom buttons on alertify confirm dialog box

I am using Alertify js 1.6.1 to show dialog box when user leaves a page. Apart from Ok and Cancel, I need to add one extra button "continue" in alertify js confirm dialog box. Is there a way to add custom button functionality? Let me know if you have any ideas on it. Thanks

You can build your own or extend the existing confirm:

    alertify.dialog('myConfirm', function() {
      var settings;
      return {
        setup: function() {
          var settings = alertify.confirm().settings;
          for (var prop in settings)
            this.settings[prop] = settings[prop];
          var setup = alertify.confirm().setup();
          setup.buttons.push({ 
            text: '<u>C</u>ontinue',
            key: 67 /*c*/ ,
            scope: 'auxiliary',
          });
          return setup;
        },
        settings: {
          oncontinue: null
        },
        callback: function(closeEvent) {
          if (closeEvent.index == 2) {
            if (typeof this.get('oncontinue') === 'function') {
              returnValue = this.get('oncontinue').call(this, closeEvent);
              if (typeof returnValue !== 'undefined') {
                closeEvent.cancel = !returnValue;
              }
            }
          } else {
            alertify.confirm().callback.call(this, closeEvent);
          }
        }
      };
    }, false, 'confirm');

see example