mod_rewrite trailing slash with RewriteCond

Question

I have searched through the related mod_rewrite qustions but I can't anything specific enough so I'll post:

Heres my rule that adds a trailing slash:

RewriteCond %{REQUEST_URI} ^/[^\.]+[^/]$
RewriteRule ^(.*)$ http://%{HTTP_HOST}/$1/ [R=301,L]

Only I want to exclude one specific directory eg. /mydirectoryname/ and not add the trailing slash to anything that starts with that. Reason being its breaking some of my ajax calls.

Answer 1

Add another RewriteCond:

RewriteCond %{REQUEST_URI} !/mydicrectoryname)/

Answer 2

You can descibe that with just one condition:

RewriteCond $0 !^mydirectoryname(/|$)
RewriteRule ^[^\.]+[^/]$ /$0/ [R=301,L]