I am making a web app that uses a Node.js/Express backend and a React.js Frontend. Right now I have my Node.js code that validities login/registration credentials in a separate folder running on localhost:5000 while my React.js frontend login/registration form code is running on localhost:3000.
My question is would it be easier to put both my frontend and backend code into one file structure so I don't have to send the data from my form to my backend running on another domain so for example both my Node.js and React.js code would be running on localhost:3000 and would just send the form information to the Node.js files that validate the user credentials instead of having to use a fetch method to send my form data to the backend. Is this even possible?
Yes, it is possible, you can use Express to serve your static files (frontend ReactJS) and also your backend routes. Take the following Github repository as an example.
That is possible, A monolithic architecture with express and reactjs (https://medium.com/@sesitamakloe/easy-express-react-monolith-chapter-1-a1567c6ff483)