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Our state is an object which in our case only has one key called message.Ĭlass Hello extends React. To initialize the state, simply set this.state in the constructor() method of the class. So if you want the data in your app to change - for example, based on user interactions - it must be stored in a component’s state somewhere in the app. And unlike props - which can’t be changed directly by the component - the state can. The other way of storing data in React is in the component’s state. However, what if we want the component to be able to change its own data? Then we have to use state instead! So now we have a reusable component which can render whatever message we want on the page. The reason we’re writing with curly braces is because we need to tell the JSX that we want to add a JavaScript expression. We can access this prop inside the Hello component by referencing, like this:Īs a result, this is rendered on the screen: This prop is called message and has the value “my friend”. This is how you pass props to a component: To achieve this type of reusability, we’ll add props. For example to display different messages. However, a big part of React is reusability, meaning the ability to write a component once, and then reuse it in different use cases. It renders out the same message no matter what. Our Hello component is completely static. It’s passed down from components higher up the hierarchy, who also control the data.Ī component can change its internal state directly. Props are external, and not controlled by the component itself. The key difference is that the state is private and can be changed from within the component itself. It’ll become easier once you start working with them. The difference between the two is a bit tricky to understand in the beginning, so don’t worry if you find it a bit confusing. There are two types of data in React: props and state. The next step is to get our app to handle data. Though what you write there does end up as HTML tags in the DOM. It’s not actually HTML, it’s a lot more powerful.

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The HTML’ish syntax we just looked at ( and ) is the JSX code I mentioned earlier. So we’re simply saying: Hey React! Please render the Hello component inside the DOM node with an id of root! So this is where we connect our Hello component with the entry point for the app (). To get our tiny application to render on the screen, we also have to use ReactDOM.render(): In the case above, we simply want it to display an h1 tag with the text Hello world! inside it. Inside render() you’ll return a description of what you want React to draw on the page. In our example, we only have one method, and it’s called render(). You then define the methods for the component. You create a component by extending upon the React-Component class. If you want to experiment with the code, check out this Scrimba playground.Įverything in React is a component, and these usually take the form of JavaScript classes. This is where we’ll write our React code. There are more two things I want you to notice: We’ll need to transform the JSX into plain JavaScript, so that the browser can understand it. We’ve also imported Babel, as React uses something called JSX to write markup. When getting started with React, you should use the simplest setup possible: an HTML file which imports the React and the ReactDOM libraries using script tags.

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I’ll leave out everything which I don’t think is core.Īnd then if it sparks your interest, and you want to learn more, you can check out our free React course on Scrimba.īut as for now, let's focus on the basics! This tutorial will give you a basic understanding of React by building a very simple application.

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