![]() ![]() We use it exactly the same way we use the div to wrap the elements in the InputField element. Meet Fragments Officiallyįragments let you group a list of children without adding extra nodes to the DOM. The good news is that React fragments solve this problem. So breaking such relationship by introducing an extra div makes styling more complicated. These mechanisms depend on the relationship that exists between parent and child elements. It makes the use of CSS mechanisms like FlexBox and CSS Grid more complicated. Adding extra DOM nodes lead to increased memory usage. But in very large applications, performance is important. Adhering to this rule might mean adding an extra DOM node even when it is not necessary. That is, a JSX expression must have only one outermost element. This might have very little impact on small applications. React Fragments 11 March, 2019 es6 javascript react Part of the JSX syntax is that adjacent JSX elements are wrapped in an enclosing tag. If we do this for a lot of other components, we will have so many extra nodes in the DOM. In React, whenever you want to render something on the screen, you need to use a render method inside the component. Introducing an extra and unnecessary node into the DOM leads to more DOM clutter. You can read more about React's StrictMode in the official docs.Here are some issues related to this addition: There's also a 'NamedExoticComponent' interface which includes the displayName (responsible for exhibiting the component name when debugging in React Devtools), but it doesn't make sense to apply it in this context as the fragment serves as a wrapper to its children and will not render any visible UI.Īnother example where an ExoticComponent interface is applied is the component React.StrictMode which also doesn't result in attaching a new node to the DOM and is used for debugging purposes while in development mode. The reason this ExoticComponent interface exists is that a component like React.Fragment should not attach its static methods to the component itself, but to the original function. The way to handle it being a valid JSX element and access its props is by pretending that it is a normal component. Although it doesn't behave like the other types of components (FunctionComponent is the main one now as StatelessComponent has been deprecated with the introduction of hooks), there's no other way implemented to tell the JSX parser that this is a JSX element type. This is exactly the case for React.Fragment. This declaration allows for developing a special kind of component that would not act as a regular React component. But what about the ExoticComponent interface, what does it have to do with react fragments? The second part makes a lot of sense as the nodes added to the DOM are the children nodes of the fragment component we apply. It is declared using the ExoticComponent TypeScript interface and it specifies a prop `children` which is set to be a ReactNode. Bonus - A look into the internals of React Fragmentīy digging into the react codebase we can tell how the React.Fragment component works internally. The fragments can be applied directly to the return of a React component, inside functions that return JSX, in conditional rendering, and pretty much anywhere else a valid react component can be used.īesides avoiding adding an unnecessary element to the DOM, fragments are also the solution to not break the rules of the HTML syntax, as in the `` element example where its parent node must be either ``, `` or ``. ![]() If there's no key or attributes set, the short syntax can be applied and both approaches deliver the same result. React Fragment helps in returning multiple elements. ![]() An example would be when mapping items from an array to JSX. Most of the times we need to return multiple elements from a component. The most common case where the full syntax is required is when dealing with cases where a key is required by React so that, internally, it can uniquely identify a given node. What is a fragment When working in React, its a common pattern to return multiple elements by wrapping them with a container element like div. ![]()
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