Directory path calls, strange behaviour - php

Question

I have an ajax request that I'm trying to call a specific file from which is located at:
ROOT/admin/functions/upload/filename.php
And the page making the request from is located at:
ROOT/admin/customers/123
Which is modified through htaccess from
ROOT/admin/customer.php?id=123
I have tried every combination of paths I could think of but I get some strange behaviours for example when I use
../functions/upload/filename.php
It looks for the file in
ROOT/functions/uploads/filename.php
And when I use
functions/upload/filename.php
It looks for the file in
ROOT/admin/customers/functions/uploads/filename.php
So I tried
../admin/functions/upload/filename.php
And it looks in
ROOT/admin/admin/functions/upload/filename.php
I'm pulling my hair out here, has anyone got any ideas as to what this might be?
Any help would be greatly appreciated.
Thanks, James.

Answer 1

Since the browser knows NOTHING about your server-side paths, and it only has the path you see in the address bar, e.g.
http://example.com/ROOT/admin/customers/123
then if your ajax code looks like
$.ajax('functions/foo/bar.php');
Then the ajax call will be requesting
http://example.com/ROOT/admin/customers/123/functions/foo/bar.php
Similarly, adding ../ just strips off levels of the source page's address:
$.ajax('../../functions/foo/bar.php');
results in
http://example.com/ROOT/admin/customers/123/../../functions/foo/bar.php
^-A-^
^-------B------^
http://example.com/ROOT/admin/functions/foo.bar.php
You probably want
$.ajax('/ROOT/functions/foo/bar.php');
With that leading /, the browser ignores ALL of the subdirectory stuff in the url and uses the entire path from the ajax call as the entirety of the path.
http://example.com/ + /ROOT/functions/foo.bar.php