We use the map() function to iterate over the list and render the results. In real-world programming, you will need the components to interact with each other. States are private to a component, but you need to pass the data between components.

React Lessons

If you click on a square now, you should see a log saying “clicked!” in the Console tab at the bottom of the Browser section in CodeSandbox. Clicking the square more than once will log “clicked!” again. Repeated console logs with the same message will not create more lines in the console. Instead, you will see an incrementing counter next to your first “clicked!” log. To build for the web, developers use React in tandem with ReactDOM. React and ReactDOM are often discussed in the same spaces as — and utilized to solve the same problems as — other true web development frameworks.

How to Bootstrap our React Project

To fix this you’ll need to group your squares into rows with divs and add some CSS classes. While you’re at it, you’ll give each square a number to make sure you know where each square is displayed. Click on the file labeled index.js in the Files section of CodeSandbox.

There are various patterns you can use as solutions to common problems in React. Over time, ReactJS developers have found patterns they could use to help them stop reinventing the wheel. We should give users the choice of what theme they want – like light or dark – to use to help them feel comfortable when using your site or app. Also, if you need to share some values between components that are not part of a hierarchy, you need a mechanism.

It’s time to learn modern React (with Hooks) the right way

For instance, React Native can be used to build mobile applications. When you click the button, the onClick handler fires. Each button’s onClick prop was set to the handleClick function inside MyApp, so the code inside of it runs.

  • The Board component now maintains which squares are filled.
  • You won’t be editing this file during the tutorial but it is the bridge between the component you created in the App.js file and the web browser.
  • By moving state up, you’ve shared it between components.
  • The handleClick function can read the squares state and call the setSquares method because they are both defined inside of the Board function.

Calling useState(), you will get back a new state variable, and a function that we can call to alter its value. We’re adding the component as if it was part of the HTML language. As introduced React Lessons in the last section, one of the main benefits of JSX is that it makes it very easy to build a UI. If you are unsure which version of npm you have, run npm -v to check if you need to update.

Using JSX to compose a UI

React will only re-run the side effect if one of the items in this array changes. The state is the set of data that is managed by the component. We are writing this UI code in a JavaScript file, and class in the JavaScript programming language is a reserved word.

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