Implementing Autosave Functionality for Long, Multi-page Forms in WordPress

You can use JS localStorage to store the data (as JSON for example) and then dynamically pull this data from localStorage and pass everything to the proper fields. In this case, you won’t need to make any AJAX requests and use your database memory. The only caveat is that your users won’t be able to use this data if they use another device or browser.

Alternatively, you can still use your MySQL database to store the data as JSON or serialize it and pull it when a user returns to the form.

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