Problem with app.js on dynamic routes

Greetings.

I’m trying to use dynamic routes like /users/:user_id but when I try to enter to said page, it only shows a blank page.

The console thows an error: that is looking for the file “http://localhost:8080/users/js/app.js” .

I’m using browserHistory, can someone tell me where to set the default route for the app.js file