Simple whole-site A/B test rules for htaccess

htaccess

# The rules below allow you to A/B test any page on your site by splitting traffic to one of two 
# sub-pages depending on the timestamp when they visit. If the millisecond is an even number, 
# they are redirect to /a/ if the millisecond is odd they go to /b/. This ensures a statisticaly 
# even split since the probability of the second being even or odd is about 50/50.
#
# You will need to create 3 sub-pages on your site: @, a, b so you'll end up with :
#
# https://yourdomain.com/@/any-page-name
# https://yourdomain.com/a/any-page-name
# https://yourdomain.com/b/any-page-name
#
# NOTE : You can change the @, a, and b to anything you like, just be sure to update the rules accordingly.
#        I do not recommend changing any of the other rules unless you really know what you are doing.
#        If you /are/ an expert and can sugget simplifications or improvements to the rules, it would 
#        be greatly appreciated.
#
# The flow will be that a user comes to https://yourdomain.com/@/some-page and be redirected to 
# either https://yourdomain.com/a/some-page or https://yourdomain.com/b/some-page
#
# So any link you use that starts with /@/any-page will be redirected to the same page name 
# under /a/ or /b/ depending on the timestamp on their first visit.

<IfModule mod_rewrite.c>

    RewriteEngine On

    # May be required to access sub directories

    RewriteBase /
    
    # ############################### #
    #        A/B TESTING (START)      #
    # ############################### #

    # (1) Check if our cookie is already set.
    #     If so, redirect to the previously-viewed page.

    RewriteCond %{HTTP_COOKIE} ab_test_vers=([^;]+)
    RewriteRule ^@(.*)/?$ HTTPS://YOUR-DOMAIN-COM/tracking/%1/$1 [cookie=ab_test_vers_match:true:YOUR-DOMAIN-COM,L]

    # (2) If no cookie is set (new visitor)
    #     AND the current time is on an even-numbered second
    #     Rewrite to /test-option-a AND set our cookie

    RewriteCond   %{HTTP_COOKIE} !ab_test_vers=([^;]+)
    RewriteCond   %{TIME_SEC} [02468]$
    RewriteRule   ^@/(.*)/?$ /tracking/even/$1 [cookie=ab_test_vers:even:YOUR-DOMAIN-COM,L]
    RedirectMatch 302 ^/tracking/even/(.*/?)$ HTTPS://YOUR-DOMAIN-COM/a/$1

    # (3) If no cookie is set (new visitor)
    #     AND the current time is on an odd-numbered second
    #     Rewrite to /test-option-a AND set our cookie

    RewriteCond   %{HTTP_COOKIE} !ab_test_vers=([^;]+)
    RewriteCond   %{TIME_SEC} [13579]$
    RewriteRule   ^@/(.*)/?$ /tracking/odd/$1 [cookie=ab_test_vers:odd:YOUR-DOMAIN-COM,L]
    RedirectMatch 302 ^/tracking/odd/(.*/?)$ HTTPS://YOUR-DOMAIN-COM/b/$1

    # ############################### #
    #        A/B TESTING (END)        #
    # ############################### #
</IfModule>