src/Builder.js
/**
   * Ask if the user wants to exit the page (to avoid unplanned refresh).
   */
Ask if the user wants to exit the page (to avoid unplanned refresh).
Ask if the user wants to exit the page ( to avoid unplanned refresh ) .
_setup_confirm_before_exit () {
    window.onbeforeunload = function (e) {
      e = e || window.event
      return  (this.options.never_ask_before_quit ? null :
               'You will lose any unsaved changes.')
    }.bind(this)
  }
_setup_confirm_before_exit ( ) { window . onbeforeunload = function ( e ) { e = e || window . event return ( this . options . never_ask_before_quit ? null : 'You will lose any unsaved changes.' ) } . bind ( this ) }
Ask if the user wants to exit the page (to avoid unplanned refresh).
Ask if the user wants to exit the page ( to avoid unplanned refresh ) .
// If we haven't been passed the event get the window.event