Quick look around
We are going to be looking at the src directory, but first:

tsconfig.json

This file contains the config for the TypeScript compiler; here's couple of interesting lines to check out:
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"target": "es5"
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Version of JavaScript standard to compile to. ES5 is fine for semi-modern browsers, ES6 can be used for controlled environments (like node).
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"strict": true
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Enables 4 flags:
  • alwaysStrict - enables JavaScript strict mode for every emitted file
  • strictNullChecks - forces better checks for null/undefined
  • noImplicitAny - forces typing for variables/arguments
  • noImplicitThis - forces typing for this, preventing context sheningans
:warning: Personal opinion: should be turned on for ALL new projects, but it's probably a good idea to turn this option to false for existing codebases.

src/App.css

Styles for the App component.

src/App.test.tsx

Unit tests for the component.

src/App.tsx

Finally, the component file itself. There's some code written already that we'll replace.
  • capital "A" - all component names (and filenames) should be written in upper camel case, without any pre- or suffixes. ( :warning: according to AirBnB style-guide )
  • export default App; - default exports are a standard practice for React.
  • return ( ... - allows for better formatting
By the way, .tsx stands for TypeScript + JSX.

src/index.tsx

Entry point of the whole operation, starts our React app with the ReactDOM.render line. This is where most of the global stuff, like global styles, should go.

src/index.css

Global styles

src/logo.svg

Not interesting in itself, but why here and not in /public directory? /public contains only truly static assets, while importing them into the component file allows for easier usage and webpack transformations.

src/react-app-env.d.ts

Typings for the React environment internals. Not interesting from the app development standpoint, but removing it will break the project.

src/serviceWorker.ts

Contains the code for a default service worker enabling PWA style app. Also, all files that don't contain components should be named using the lower camel-case style.

Resources