How does Wechat web developer monitor and close web pages?

how do I monitor this behavior before closing Wechat"s web page? Similar to JD.com Shopping prompts "whether to quit" before quitting the page

Wechat-develops javascript
Aug.15,2021 
window.onbeforeunload=function(e){     
var e = window.event||e;  
e.returnValue=("");
}

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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-64f5-1b3088e-2bd2b.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b3088e-2bd2b.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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