In today’s article for React basics, we’ll enhance our first ever React components with a list.
Yesterday we made some static book components like so:
<Book title='Laravel collections' />
<Book title='Ruby for beginners' />
<Book title='CSS is awesome' />
However, that quickly becomes a struggle to maintain. So let’s look at how we could dynamically load these books from a list.
Creating a list in React
Open up your App.js and add a list like so above your app declaration.
const books = [
{
id: 1,
title: 'Laravel collections',
},
{
id: 2,
title: 'Ruby for beginners',
},
{
id: 3,
title: 'CSS is awesome',
},
];
function App() {}
We can leverage the’ map’ function to render these elements in our React app.
<Bookshelf>
{books.map((book) => (
<Book title={book.title} />
))}
</Bookshelf>
And this little piece of code will do the same thing as before.
Keys in React
However, I made one big mistake in the example above. When we render list items in React as we do above, we should always set a key property. This key will help React identify which items change or should be removed.
To add the key, we can use the following code.
<Book title={book.title} key={book.id} />
However, sometimes we do not have a key, so what do we do then?
Well, no worries, React comes with a built-in index we can use as the key.
const numbers = [1, 2, 3];
{
numbers.map((number, index) => <span key={index}>Number: {number}</span>);
}
As you can see, the index is available on the map function as the unique key for each element.
You can find this code on GitHub. I hope you enjoyed this article about loops in React.
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