What you're trying to achieve is like offline versions of forms. If so, you can automatically save the data of the user in the localStorage (HTML5).
https://developer.mozilla.org/en-US/docs/Web/Guide/API/DOM/Storage[
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You can save the data the user would input in the localStorage, and upon the Save button clicks, you can validate the data. Note that there are many methods to validate the data. Using client-side code as well as using server-side code.
It depends on how you want to implement the validation to your data.