PHP cannot obtain Referer for troubleshooting

: This article mainly introduces how to troubleshoot the problem that PHP cannot obtain Referer. if you are interested in the PHP Tutorial, refer to it. Test results:

The same page is opened twice. the Referer cannot be obtained twice for the first time. I'm curious about the reason.

The test1.php code is:

 '; Echo' to go to the page
'; Echo' Test Source: New window opens
'; Echo' to go to the page
';

The code for test_cookie.php is:

 \ R \ n "; echo 'php gets Refer: '; $ refer = isset ($ _ SERVER ['http _ referer'])? $ _ SERVER ['http _ referer']: 'No refer found '; echo $ refer; echo"
\ R \ n "; echo 'JS get Refer: '; echo" script document. writeln (document. referrer); script "; echo"
\ R \ n ";

I am extremely curious about what causes the first retrieval and the second retrieval.

The environment is LNMPA, the official is http://lnmp.org/lnmpa.html

Use charles to capture packets on Mac

The headers of test1.php are the same for two requests.

The headers of the two request test_cookie.php are consistent.

The problem arises. Why does PHP fail to obtain a refer for two identical requests. Begging for solutions.

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The above describes how to troubleshoot the problem that PHP cannot obtain Referer, including related content, and hope to help those who are interested in PHP tutorials.