How does the following URL jump from PC station to M station?

typing http://www.zhen.com on your phone will jump to http://m.zhen.com, but the http status code of http://www.zhen.com is 200 OK , not 30X . You can"t figure out how to jump

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Mar.17,2021

http://www.zhen.com has the following passage on its web page:

<script>
if((navigator.userAgent.match(/(phone|pad|pod|iPhone|iPod|ios|iPad|Android|Mobile|BlackBerry|IEMobile|MQQBrowser|JUC|Fennec|wOSBrowser|BrowserNG|WebOS|Symbian|Windows Phone)/i))){
     window.location.href = "http://m.zhen.com";
}
</script>

you can use the computer to see for yourself. Because it is a direct refresh operation, it must be 200

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-64f5-1b377ed-2c0b0.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b377ed-2c0b0.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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