Set up this project to document some sample code since I have been focused in private repos for over 5 years.

• Check the commit logs and commit messages for an up to date inventory of skills demonstrated

React now offers useState in its hooks useState has other functions like activeIndex and setActiveIndex

Old school methods for writing this, and then gradual refactors

const things = useState(null)
const activeIndex = things[0]
const setActiveIndex = things[1]

• but you can also skip the first step, and directly assign the variables through array destructuring

[ activeIndex: activeIndex, setActiveIndex:setActiveIndex ] = useState(null)

• plus, since the names of the variables are identical in the new array to the variable names, you can even skip the assignment because

activeIndex
activeIndex: activeIndex

• are identical in compilation time when declared within an array

so the entire statement can be reduced further to

[ activeIndex, setActiveIndex ] = useState(null)

Which pulls useState from 'react', declares activeIndex and setActiveIndex from useState, and assigns those functions by name, with activeIndex being simply a variable which defines a piece of state, and setActiveIndex being a means for updating it.

null represents the only parameter needed for useState(), which is whatever initialization value you want to start with.

Very concise!

This project was bootstrapped with Create React App.

In the project directory, you can run:

Runs the app in the development mode.
Open http://localhost:3000 to view it in your browser.

The page will reload when you make changes.
You may also see any lint errors in the console.

Launches the test runner in the interactive watch mode.
See the section about running tests for more information.

Builds the app for production to the build folder.
It correctly bundles React in production mode and optimizes the build for the best performance.

The build is minified and the filenames include the hashes.
Your app is ready to be deployed!

See the section about deployment for more information.

Note: this is a one-way operation. Once you eject, you can't go back!

If you aren't satisfied with the build tool and configuration choices, you can eject at any time. This command will remove the single build dependency from your project.

Instead, it will copy all the configuration files and the transitive dependencies (webpack, Babel, ESLint, etc) right into your project so you have full control over them. All of the commands except eject will still work, but they will point to the copied scripts so you can tweak them. At this point you're on your own.

You don't have to ever use eject. The curated feature set is suitable for small and middle deployments, and you shouldn't feel obligated to use this feature. However we understand that this tool wouldn't be useful if you couldn't customize it when you are ready for it.

You can learn more in the Create React App documentation.

To learn React, check out the React documentation.

This section has moved here: https://facebook.github.io/create-react-app/docs/code-splitting

This section has moved here: https://facebook.github.io/create-react-app/docs/analyzing-the-bundle-size

This section has moved here: https://facebook.github.io/create-react-app/docs/making-a-progressive-web-app

This section has moved here: https://facebook.github.io/create-react-app/docs/advanced-configuration

This section has moved here: https://facebook.github.io/create-react-app/docs/deployment

This section has moved here: https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify