Practical approach for design a todo-app

I try to make a todo-app using react/(maybe)redux. My goal is to have a client that cant communicate with server using RESTful API to fetch and update data.

I already wrote my server that can handle AJAX request and host it on heroku.

My next step is to create a front-end using react or react/redux. Im not sure what is the right approach to store and update data.

Should I fetch and update data directly from client to server? If this the case, I think I only need to use react, do I ?

The second approach, I guess I need to use react and redux, is to fetch the "initial" data from server and store in reducers, display and change whatever user wants. Then, at the end, update the data back to server.

Im still learning web dev. I really appreciate any suggestion or documents that I can read