RewriteEngine On
# If an existing asset or directory is requested go to it as it is
RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} -f [OR]
RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} -d
RewriteRule ^ - [L]
# If the requested pattern is file and file doesn't exist, send 404
RewriteCond %{REQUEST_URI} ^(/[a-z_-s0-9.]+)+.[a-zA-Z]{2,4}$
RewriteRule ^ - [L,R=404]
# otherwise use history router
RewriteRule ^ /index.html