(<>...</>) – React (original) (raw)

<Fragment>, often used via <>...</> syntax, lets you group elements without a wrapper node.

<>

<OneChild />

<AnotherChild />

</>

• Reference
• Usage
  • Returning multiple elements
  • Assigning multiple elements to a variable
  • Grouping elements with text
  • Rendering a list of Fragments

Reference

<Fragment>

Wrap elements in <Fragment> to group them together in situations where you need a single element. Grouping elements in Fragment has no effect on the resulting DOM; it is the same as if the elements were not grouped. The empty JSX tag <></> is shorthand for <Fragment></Fragment> in most cases.

Props

• optional key: Fragments declared with the explicit <Fragment> syntax may have keys.

Caveats

• If you want to pass key to a Fragment, you can’t use the <>...</> syntax. You have to explicitly import Fragment from 'react' and render <Fragment key={yourKey}>...</Fragment>.
• React does not reset state when you go from rendering <><Child /></> to [<Child />] or back, or when you go from rendering <><Child /></> to <Child /> and back. This only works a single level deep: for example, going from <><><Child /></></> to <Child /> resets the state. See the precise semantics here.

Usage

Returning multiple elements

Use Fragment, or the equivalent <>...</> syntax, to group multiple elements together. You can use it to put multiple elements in any place where a single element can go. For example, a component can only return one element, but by using a Fragment you can group multiple elements together and then return them as a group:

function Post() {

return (

<>

<PostTitle />

<PostBody />

</>

);

}

Fragments are useful because grouping elements with a Fragment has no effect on layout or styles, unlike if you wrapped the elements in another container like a DOM element. If you inspect this example with the browser tools, you’ll see that all <h1> and <article> DOM nodes appear as siblings without wrappers around them:

export default function Blog() { return ( <> </> ) }

function Post({ title, body }) { return ( <> </> ); }

function PostTitle({ title }) { return

{title}

function PostBody({ body }) { return (

Deep Dive

How to write a Fragment without the special syntax?

The example above is equivalent to importing Fragment from React:

import { Fragment } from 'react';

function Post() {

return (

<Fragment>

<PostTitle />

<PostBody />

</Fragment>

);

}

Usually you won’t need this unless you need to pass a key to your Fragment.

Assigning multiple elements to a variable

Like any other element, you can assign Fragment elements to variables, pass them as props, and so on:

function CloseDialog() {

const buttons = (

<>

<OKButton />

<CancelButton />

</>

);

return (

<AlertDialog buttons={buttons}>

      Are you sure you want to leave this page?

</AlertDialog>

);

}

Grouping elements with text

You can use Fragment to group text together with components:

function DateRangePicker({ start, end }) {

return (

<>

      From

<DatePicker date={start} />

      to

<DatePicker date={end} />

</>

);

}

Rendering a list of Fragments

Here’s a situation where you need to write Fragment explicitly instead of using the <></> syntax. When you render multiple elements in a loop, you need to assign a key to each element. If the elements within the loop are Fragments, you need to use the normal JSX element syntax in order to provide the key attribute:

function Blog() {

return posts.map(post =>

<Fragment key={post.id}>

<PostTitle title={post.title} />

<PostBody body={post.body} />

</Fragment>

);

}

You can inspect the DOM to verify that there are no wrapper elements around the Fragment children:

import { Fragment } from 'react';

const posts = [ { id: 1, title: 'An update', body: "It's been a while since I posted..." }, { id: 2, title: 'My new blog', body: 'I am starting a new blog!' } ];

export default function Blog() { return posts.map(post => ); }

function PostTitle({ title }) { return

{title}

function PostBody({ body }) { return (