In this post we will look at a way to fix that and how to fix a slightly more complicated yet still real world problem where the most common fix won’t work. If you do that, you get the following showing your browser’s console: Warning: Each child in a list should have a unique "key" prop. Moving forward, you can learn more about Lists and Keys in React.You may well have come across the warning in React where you are rendering out a list of things, and you forget to give each element a unique key. It’s good practice to avoid extra DOM nodes with the Fragment component, unless you need them. We also saw its comparison with the div element and also saw a shorter syntax for using Fragments. In this article, we’ve seen what React Fragments are, their relevance and three common use cases where this component can be very handy. But if you only need a parent component somewhere to fulfill JSX syntax without the need for a key prop, then the short syntax is your best shot. So if you’re working with arrays and you want to use the Fragment component, you have to use the long version of it. The key prop is an important prop in React components that keeps React informed of which items have changed, being added or removed in a list. The downside to using this shortcut is that you cannot use the key prop. You don’t need to import the Fragment component from the React library. Instead of having to type “Fragment” all the time when you need it, you can simply use the empty fragment tag shortcut like this: But, after compilation, the Fragment component does not get to the DOM, thereby you can not use it on the UI. React Fragment only accepts the key attribute which every element, including the div also accepts. Only the div accepts classes that you can use to style the container or the children components. However, only the div can appear on the screen. React Fragment and div can both serve as parents for grouping children components in a valid JSX syntax. The div element on the other hand is an HTML element with no semantic meaning but when used, will be added to the DOM as a node. React Fragment is a component exposed by React which serves as a parent component in JSX but doesn’t add anything to the DOM. With this, only the h2, p and span elements are added to the DOM. The Fragment component as stated earlier also accepts the key attribute for which we added a the product’s id as the value. To access the Fragment component, you can either import it from the React library like this: You should use the React Fragment when you want to add a parent element to fulfill the JSX syntax, but without introducing an extra node to the DOM.Īfter compilation, the fragment component does not make it to the DOM-only the children element do. React Fragment was created to solve problems like this, where you do not want to introduce an extra element to the DOM, and you need a parent element. affect accessibility in cases where the additional nodes may conflict with your semantic elements.produce CSS conflicts if the extra node is not acknowledged in the style declaration.affect the performance of your application (if there are a lot of them in different parts of your application). Sometimes, you may not want that additional node.Īdding extra unnecessary nodes to the DOM can cause one or all of these three things: However, this would introduce an extra node to the DOM. This parent element could be a div, a span, or whatever element that is more semantically correct to serve as the parent. The solution to both blocks would be to add a parent element. The second one would throw an error because the two span expressions do not have a parent element. The first code block would throw an error because there is no parent element before the two child divs.
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