如何使用htaccess从子URL重写到子目录？

Question

My backend is PHP and in the frontend I want to have a reactJS compiled project that I want to allow user access to via example.com/app and that compiled project's index.html file is placed in /var/www/html/reactjs/build/index.html and I need to somehow rewrite all example.com/app requests to that directory otherwise the reactJS app won't work properly / at all.

This is what I've tried to do and not working for me:

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^/app /reactjs/build/index.html [QSA,L]

IDK what else to try, I'd love to get a direction on how to solve this issue :)

Answer 1

RewriteRule ^/app /reactjs/build/index.html [QSA,L]

In .htaccess the URL-path matched by the RewriteRule pattern does not start with a slash, so this would need to be rewritten:

RewriteRule ^app /reactjs/build/index.html [L]

The QSA flag is also not required here.

UPDATE: site I'm using is a wordpress site

These directives need to go before the WordPress front-controller, otherwise these requests for /app/... will be routed to WordPress instead. For example:

# ReactJS routing...
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^app /reactjs/build/index.html [L]

# BEGIN WordPress
: