How does the Wechat official account project monitor all return operations?

Wechat"s official account project has a form page with a classification option that is a new page (the style is similar to this http://vue.ydui.org/demo/-sharp/sc., but not a front-end separation project), and the back end now wants to integrate it into one page.
because this is not single page, if the user clicks back on the category, because it is now a page, which is equivalent to quitting the form page, the previous fill-in will be filled out in vain.
there are many methods to monitor returns on the Internet, but what I need is to monitor all possible returns (the return above Wechat, the physical return button on the phone, and the user sliding back). Is there any good way?

May.05,2021

Save form data at any time
fill in
when the page is initialized

MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b366df-2c01a.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b366df-2c01a.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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