Reat App Development - Basics

Debugging in the Editor
This feature is currently only supported by Visual Studio Code and WebStorm.

Visual Studio Code
You would need to have the latest version of VS Code and VS Code Chrome Debugger Extension installed.

Then add the block below to your launch.json file and put it inside the .vscode folder in your app’s root directory.

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Chrome",
      "type": "chrome",
      "request": "launch",
      "url": "http://localhost:3000",
      "webRoot": "${workspaceFolder}/src",
      "sourceMapPathOverrides": {
        "webpack:///src/*": "${webRoot}/*"
      }
    }
  ]
}

Start your app by running npm start, and start debugging in VS Code by pressing F5 or by clicking the green debug icon. You can now write code, set breakpoints, make changes to the code, and debug your newly modified code—all from your editor.


WebStorm
You would need to have WebStorm and JetBrains IDE Support Chrome extension installed.

In the WebStorm menu Run select Edit Configurations.... Then click + and select JavaScript Debug. Paste http://localhost:3000 into the URL field and save the configuration.

Start your app by running npm start, then press ^D on macOS or F9 on Windows and Linux or click the green debug icon to start debugging in WebStorm.



References:
https://facebook.github.io/create-react-app/docs/setting-up-your-editor