It does so with the help of a special React prop called a key. If we look at the console tab at the bottom we will see a warning, saying each child in the list should have a «unique key prop.» We need to return something, specifically some JSX. Every component we make must return JSX elements and components (which must also, ultimately, be composed of JSX). We are attempting to display our TodoList component, but we haven’t created it yet.
- These topics will be the base upon which you will build in other more advanced React tutorials.
- My DMs are open on Twitter if you want to discuss further.
- React is used for frontend web apps to detect user input, fetch data, and update the user interface with data.
- Since you are recording the tic-tac-toe game’s history, you can now display a list of past moves to the player.
Learn the basics of modern React by solving 140+ interactive coding challenges and building eight fun projects. The export default keywords specify the main component in the file. If you’re not familiar with some piece of JavaScript syntax, MDN and javascript.info have great references. I am not comparing React with the Angular, Vue, or Svelte frameworks. They are all excellent in their ways, like how ReactJS is an excellent library for user interface development. Here’s a handy Redux for beginners guide that you can use to get started.
Handling user events in React
Try the first 67 lessons, challenges & flashcards for free. You can upgrade to a Pro account with a one-time payment that gives you access for 5 years. Remember that Board used to call setSquares with an updated array; now it passes the updated squares array to onPlay. The DOM element’s onClick attribute has a special meaning to React because it is a built-in component.
To fix this, you will use props to pass the value each square should have from the parent component (Board) to its child (Square). In the live code editor below, click Fork in the top-right corner to open the editor in a new tab using the website CodeSandbox. CodeSandbox lets you write code in your browser and preview how your users will see the app you’ve created. The new tab should display an empty square and the starter code for this tutorial.
React Forms
When we refer to React as a «framework», we’re working with that colloquial understanding. Learn an application framework built on top of React, like Gatsby or Next.js. The function will be run by React when the component is first rendered, and on every subsequent re-render/update. We call props the initial values passed to a component.
You should learn them along with the helpful patterns you should use. You can even create your custom themes in some applications and apply them. Select the one that matches the best with your application’s CSS stack.
Displaying data
React provides an easy way to manage events fired from DOM events like clicks, form events, and more. You need to know that there are more advanced ways to manage data, which include the Context API and libraries like Redux. But those introduce more complexity, and 90% of the times using those 2 ways I just explained are the perfect solution. Then we use them to define the function code block, and finally in the JSX to print the JavaScript value. Calling the modifier is the way we can tell React that the component state has changed.
If you prefer learning each concept step by step, start with Describing the UI. Most of all, make sure you practice by building sample applications to apply everything you’ve learned. Passing props to components React Lessons is a great way to pass values around in your application. In the last section you met your first React component, the App component defined in the default application built by create-react-app.
I hope you have a better understanding of the basics. If you look at the above two blocks of code, you will find the first one more familiar as it gives an HTML feel. Let’s have a look at another example, without JSX and with JSX to get a feel for the code readability. We’ve been talking about one of the great features of React — that is the virtual DOM but wait!
