Try deploying react app at username.github.io

First of all, create a react-app. We'll create a build for the application everytime a new change is made in default branch and serve using github-pages in that branch.

• Add gh-pages as dev-dependency in you application.
• For this, add required scripts in package.json:

    "predeploy": "npm run build"
    "deploy": "gh-pages -d build"
  

• While pushing any new changes, along with this do npm run deploy, this will create a new branch and push the build to the created branch.
• Serve using github-pages at new branch(gh-pages) in /.
• Now, to avoid overhead, add a script "push": "npm run deploy && git push" in package.json and after committing, instead of pushing it with git push, use npm run push.
• Hooray! Visit https://username.github.io and your website is live.