![]() While you may have a use case for ReactElement or JSX.Element, if you're not sure which to use, stick with ReactNode. JSX.Element is a default inferred type applied by TypeScript and is not usually what you want to define for your own components.Īs a developer it's important to use the right tool (or type in this case) for the job.But you usually don't want it for the children props on your custom components. ReactElement can be useful for reading props, type, and key properties when parsing children with one of the React.Children utilities, or perhaps building a React library.You can also safely use this type for React elements passed as "regular" props. If you're an app developer, ReactNode will usually be the preferred option for custom components that accept custom children arguments.So the answer to "when should you use ReactNode, ReactElement, or JSX.Element" is this: JSX.Element is the type that TypeScript infers and applies as a default to JSX React elements.ReactElement is useful for parsing children with utilities like. The empty JSX tag <></> is shorthand for in most cases.Grouping elements in Fragment has no effect on the resulting DOM it is the same as if the elements were not grouped. However, after reviewing the types we can see they have slightly different purposes: Wrap elements in to group them together in situations where you need a single element.It can seem confusing at first to have multiple types that seem to accomplish the same thing. However, since ReactNode has the same pre-filled-to-any behavior, and is more flexible, it's hard to recommend using JSX.Element. What could be interpreted as a slight improvement is the generics are pre-filled to any, preventing consumers from thinking children types can properly be restricted (even though TypeScript doesn't support this). This means JSX.Element has many of the same properties as ReactElement including its limitations. The Element type is a passthrough to ReactElement with any supplied as generic arguments.JSX is a global namespace meaning you don't need to import it in order to use it. ![]() Let's look at an example and see how we might want to add types to it: // måomponent.tsxÄ®xport function Måomponent( React treats children with just a little bit of magic that allows for composing React elements into more complex components. Which one should we use for adding types to children in our custom components? When to use ReactNode, ReactElement, or JSX.ElementĪ common scenario when writing custom components is to allow that component to accept children as a prop. However, these types are slightly different. booleans, null, and undefined (ignored and not provides a couple different options that seem could be used to fulfill this type definition: ReactNode, ReactElement, and JSX.Element.functions (for custom components that accept functions).JSX children (aka, nested react components).string literals (also includes numbers which are coerced to HTML strings).The react docs explain the following types can be used as children: However, one thing I have frequently gotten tripped up on is how children types are defined and intended to be used. These types are essential for developing my React + TypeScript projects. (the React team even included a great react types upgrade guide with the React 18 release). However, the react team works closely with the community to ensure types are accurate so that TypeScript can help developers use React as correctly as possible. The React type definitions ( are maintained separately from the core react library by the TypeScript community. There are some exceptions and this presents a challenge for defining accurate type definitions for React children. We even can have functions as children (aka, render props)!Ä«ut I said you can render "mostly" anything. This is EventsTable: EventsTable = React.One of the coolest features of React is that everything is "just JavaScript" (or TypeScript!) so the library mostly doesn't care what you provide as children as long as it can be rendered to the UI. See docs here Yes, you can add a key in the below form Fragment which is not possible in the shorter version of Fragments (i.e, <></>) You can also use this way to auto assign key to your component list.See fb.me/react-warning-keys for more information. React-runtime-dev.js?8fefd85d334323f8baa58410bac59b2a7f426ea7:21998 Warning: Each child in an array or iterator should have a unique "key" prop. Warning: Each child in an array or iterator should have a unique "key" prop.
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