Question

There are, say, 10 fields on page1 and hyperlink to page2. Also there is hyperlink on page2 to page1. I fill 5 fields and click on the hyperlink. Then I click on the hyperlink on page2 and return to page1. Is it possible to save filled fields and how?
Additional question: what if page2 modifies fields of page1. For example, creates new choice in multichoice field.

Answer 1

You can save filled fields using cookies via javascript after clicking on the link and before going to another page. For example it’s possible to use this jQuery plugin jQuery-cookie. As documentations says:

A simple, lightweight jQuery plugin for reading, writing and deleting cookies.

Create session cookie:
$.cookie('the_cookie', 'the_value');

Create expiring cookie, 7 days from then:    
$.cookie('the_cookie', 'the_value', { expires: 7 });

Create expiring cookie, valid across entire page:    
$.cookie('the_cookie', 'the_value', { expires: 7, path: '/' });

Read cookie:    
$.cookie('the_cookie'); // => 'the_value'
$.cookie('not_existing'); // => null

Delete cookie by passing null as value:    
$.cookie('the_cookie', null);

Note: when deleting a cookie, you must pass the exact same path, domain and secure options that were used to set the cookie.