Sometimes we want to create components with an internal state that changes overtime, imagine a traffic light that changes color every 3 seconds, for that we normally will make a variable color and set it to a default color:

let color = "blue";

But we want our component to re-render and change the website HTML every time the variable color changes, that's why we use hooks:

//        ↓ variable name             ↓ default value
const [ color, setColor] = useState("red");
//               ⬆ function to change the color

From now one, every time we use the function setColor to change the variable color, the component will re-render and the entire traffic light HTML will be updated with the new color.

You can read more about hooks here.

Do not clone this repository.

The first step to start coding is cloning the react boilerplate on your local computer or gitpod.

a) If using Gitpod (recommended) you can clone the boilerplate by clicking here.

b) If working locally type the following command from your command line: $ git clone https://github.com/4GeeksAcademy/react-hello.

💡 Important: Remember to create a new repository, update the remote (git remote set-url origin <your new url>), and upload the code to your new repository using add, commit and push.

Let's simulate a traffic light like this one.

The light has to glow when clicked.

• The whole purpose of the component is displaying a traffic light with red, yellow and green lights.
• When any light is clicked (selected) it has to glow, but the other lights have to stop glowing.
• The component must have a hooked state variable that tracks the color:

const [ color, setColor] = useState("red");

• Use the setColor function to change the color an the component will automatically re-render (because it's hooked with useState).

• Use the ReactDOM.render to render the component into the DOM like this

ReactDOM.render(<TrafficLight />, document.querySelector('#app'));