FluidSurveys: Prompting the user to "Save and continue later" before closing the window.

fluidsurveys-save-prompt.js

// 1. Add a question of type "javascript" to your survey (ultra package or higher required)
// 2. Paste this code in and edit the message.

$(function(){
//place script here

  $(window).bind('beforeunload', function(){
	return 'Just to make sure, did you click "Save and continue later"? We\'re checking because we wouldn\'t want you to lose what you entered.';
  });
  
  $('input[type=submit]').click(function(){
    $(window).unbind('beforeunload');
  });

});

One issue: it won't work on the iPad, if the user closes the Safari tab. :/