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

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