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Best Way to Use React Fragment for Easy Grouping

Would you like to learn about the importance of using React Fragment on your web app? React Fragment is a feature in React that lets you group JSX expressions without adding additional elements to the rendered page.

In this tutorial, we’ll explain what React Fragment means, and its importance in web development. We’ll also show you working examples and advanced usage of this component. Let’s dive right in.

Definition of React Fragment

React Fragments are a feature in React that allows you to group multiple child elements without adding extra nodes to the DOM. 

In React, each component must return a single root element. However, this can be restrictive when you want to return multiple elements from a component. 

React Fragments solves this problem by allowing components to return multiple elements grouped under a single parent without the need for an additional wrapping element like a <div>.

Why Use React Fragment?

Before React Fragments, developers often wrapped multiple elements in a <div> or another HTML element to satisfy React’s requirement for a single root element. This approach, however, led to the introduction of unnecessary DOM nodes. 

An extra node can lead to bloated DOM trees, affecting performance and complicating CSS styling and manipulation with JavaScript.

React Fragments addresses this issue by allowing developers to wrap multiple elements from a component into only one element. This results in a cleaner, more efficient DOM structure. 

Fragments are especially useful in scenarios like rendering lists, table data, or any other place where wrapping elements in a <div> would break the desired HTML structure.

Understanding React Fragments

Like we mentioned earlier, React Fragments allow developers to return multiple elements from a component without adding unnecessary divs. This section will explain how they work.

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Basic Syntax of React Fragments

There are two syntaxes available for declaring React Fragments:

Short Syntax (<> </>): This is the most common and concise way to declare a Fragment. It doesn’t support keys or attributes, making it ideal for simple groupings of elements.

<>
 <ChildA />
 <ChildB />
 <ChildC />
</>

Long Syntax (<React.Fragment> </React.Fragment>): This syntax is more verbose but necessary in scenarios where you need to pass key props, which is common in lists.

<React.Fragment key={item.id}>
  <ChildA />
  <ChildB />
</React.Fragment>
FeatureShort Syntax (<> </>)Long Syntax (<React.Fragment> </React.Fragment>)
DescriptionA concise way to write React Fragments.The more explicit syntax for defining Fragments.
Support for KeysDoes not support keys.Supports keys, which is useful for rendering lists of items.
Support for AttributesDoes not allow attributes.Allows attributes, like key.
Use CaseIdeal for simple cases where you just need to group elements without extra nodes.Necessary when you need to assign a key to each item in a list or need to pass other attributes.
VerbosityLess verbose, cleaner syntax.More verbose but clearer in intent, especially for those unfamiliar with the short syntax.
CompatibilityMight not be supported in all tools or older versions of React.Generally supported in all environments that use React.

When and Why to Use React Fragments

React Fragments should be used to group multiple elements without adding additional DOM nodes. This is essential for the following reasons:

  • Maintaining the correct structure: Adding extra <div> elements can break the layout in certain HTML structures like tables.

  • Performance: Reducing unnecessary DOM nodes can improve the performance of your application.

  • Cleaner DOM: It leads to a cleaner, more readable DOM, which is easier to manage, especially in CSS and JavaScript manipulations.

Scenarios Where Fragments are Beneficial

Here are some common situations where using React Fragments can be particularly useful:

  1. Grouping Multiple Child Components Without Extra Markup: When a component needs to return multiple elements and you don’t want to add extra nodes to the DOM. React Fragments allow you to group these elements seamlessly.

  2. Rendering Lists or Collections: When mapping over an array to create a list of elements, React Fragments can be used to wrap each group of elements. This is especially useful when each list item consists of multiple HTML elements.

  3. Maintaining Proper HTML Structure: In certain HTML structures like tables, wrapping elements in a <div> can break the layout. Fragments allow you to add multiple elements without disturbing the structure.

  4. Conditional Rendering of Groups of Elements: Fragments are useful when you want to conditionally render a block of elements. Instead of wrapping them in a <div>, you can use a Fragment to keep the DOM clean.

  5. Improving Performance by Reducing DOM Nodes: In complex applications with many components, unnecessary DOM nodes can impact performance. Fragments help reduce the number of nodes, leading to better performance.

React Fragment vs Divs and Other Wrapper Elements

React Fragments differ from <div> or other wrapper elements in several ways:

  • No Impact on Styling: Unlike <div>, Fragments don’t affect CSS styling as they don’t create a new node in the DOM.

  • No Impact on Layout: Fragments do not interfere with the layout. Using a <div> might disrupt the flow of the document, especially in flexbox and grid layouts.

  • Performance: As Fragments reduce the number of nodes in the DOM, they can potentially lead to performance improvements in complex applications.

Practical Usage of React Fragments

Let’s explore some practical use cases of the React fragment component.

Grouping Multiple Elements

React Fragments are incredibly useful for grouping multiple sibling elements without adding extra nodes to the DOM. This is particularly beneficial in maintaining the correct HTML structure and optimizing performance.

  • Grouping List Items: In cases where you want to render a list of items without wrapping them in an extra <div>, React Fragments allows you to group these list items directly under <ul> or <ol>.

    <ul>
      {items.map(item => (
        <React.Fragment key={item.id}>
          <li>{item.name}</li>
          <li>{item.description}</li>
        </React.Fragment>
      ))}
    </ul>
  • Table Rows: When creating tables, using <div> tags disrupts the table structure. Fragments let you group multiple <td> or <tr> elements correctly within a <table>, <tbody>, or <thead>.

    <table>
      <tbody>
        {data.map(row => (
          <React.Fragment key={row.id}>
            <tr>
              {/* Table Cells */}
            </tr>
          </React.Fragment>
        ))}
      </tbody>
    </table>

2. Handling Conditional Rendering

Fragments can also be used effectively in conditional rendering scenarios. They provide a way to return multiple elements without altering the DOM structure unnecessarily.

Here is an example. You might want to render multiple elements conditionally without wrapping them in an unnecessary <div>. React Fragments make this possible, keeping the code clean and efficient.

{shouldDisplayDetails && (
  <>
    <DetailComponentA />
    <DetailComponentB />
  </>
)}

3. With Higher Order Components (HOCs)

Higher Order Components (HOCs) in React are used to reuse component logic. React Fragments can be integrated into HOC patterns to return multiple elements from a component.

Here is an example. When a HOC wraps a component, you might need to return multiple elements without disturbing the surrounding DOM structure. Fragments allow the wrapped component to return a group of elements as one entity.

const withEnhancement = WrappedComponent => props => (
  <React.Fragment>
    <WrappedComponent {...props} />
    <AdditionalComponent />
  </React.Fragment>
);

Practical Example

Let’s create a practical example of a React component that uses Fragments to render a table. We’ll have two components: App and TableData. The TableData component will be responsible for rendering the data in the table, and it will be used within the App component.

For this example, we assume you already have a React application ready. Please watch the video below if you need help setting up a React project.

First, let’s define some sample data and the TableData component:

// TableData.js
import React from 'react';

const TableData = ({ data }) => {
  return data.map(item => (
    <React.Fragment key={item.id}>
      <tr>
        <td>{item.id}</td>
        <td>{item.name}</td>
        <td>{item.age}</td>
      </tr>
    </React.Fragment>
  ));
};

export default TableData;

In TableData.js, we map over the data prop, returning a table row for each item. We wrap each row in a React.Fragment with a unique key (item.id).

Next, we’ll use this TableData component in our main App component:

// App.js
import React from 'react';
import TableData from './TableData';

const App = () => {
  const sampleData = [
    { id: 1, name: 'Alice', age: 30 },
    { id: 2, name: 'Bob', age: 24 },
    { id: 3, name: 'Carol', age: 31 },
  ];

  return (
    <table>
      <thead>
        <tr>
          <th>ID</th>
          <th>Name</th>
          <th>Age</th>
        </tr>
      </thead>
      <tbody>
        <TableData data={sampleData} />
      </tbody>
    </table>
  );
};

export default App;

In App.js, we define some sample data and render a table. The TableData component is used within the <tbody> element to render each table row.

This example showcases how React Fragments can be effectively used in a component structure to render lists of items, such as table rows, without introducing unnecessary DOM nodes.

This approach keeps the DOM structure clean and straightforward, which is particularly important for complex components like tables.

Advanced Concepts

Keys are essential in React for helping the framework identify which items in a list have changed, been added, or removed.

This concept also applies to Fragments, especially when they are used to wrap elements in a list.

In scenarios where you map over an array to create a list of elements grouped by Fragments, each Fragment needs a unique key. This key helps maintain state and lifecycle status across re-renders for each group of elements.

Example: Imagine rendering a list where each list item consists of multiple elements (like a title and description), and you want to group these elements without an additional DOM node:

<ul>
  {items.map(item => (
    <React.Fragment key={item.id}>
      <h3>{item.title}</h3>
      <p>{item.description}</p>
    </React.Fragment>
  ))}
</ul>

In the above code, each React.Fragment is assigned a unique key (item.id), which is essential when rendering dynamic lists.

Performance Considerations

Impact of Fragments on Rendering Performance: React Fragments positively impact rendering performance, particularly when reducing the number of DOM nodes is beneficial. Fragments help keep the DOM tree lean and efficient by avoiding extra wrapping elements.

  • Reduced Overhead: Fewer DOM nodes mean less overhead for the browser’s rendering engine. This can lead to improved rendering and re-rendering performance.

  • Cleaner DOM Tree: A cleaner DOM tree is easier for browsers to parse and render. It also makes it easier to manage and debug your application.

  • No Deep Nesting: Fragments avoid the need for deeply nested trees of elements, which can be costly in terms of performance and readability.

Example Scenario: Consider a complex application with many components, each comprising multiple child elements. Wrapping each component in an unnecessary div could lead to hundreds of unnecessary DOM nodes. Fragments can significantly reduce the number of DOM nodes, leading to better performance, especially when the list is frequently updated or re-rendered.

In summary, using React Fragments judiciously can positively improve the performance of your web application. They allow you to build complex, dynamic UIs without the overhead of extra DOM elements, thereby keeping your application efficient and responsive.

Best Practices and Common Mistakes

Let’s discuss some best practices and mistakes to avoid when using React fragments.

Do’s

  1. Use When Necessary: Employ Fragments when you need to return multiple elements from a component without adding an extra node.

  2. Utilize Keyed Fragments for Lists: In scenarios involving lists or iterable data, use keyed Fragments (<React.Fragment key={keyValue}>) to help React identify and manage list items efficiently.

  3. Keep the DOM Clean: Use Fragments to prevent unnecessary nesting and keep your DOM structure clean and efficient.

Don’ts

  1. Overuse: Avoid using Fragments excessively or without necessity. Not every component or element grouping requires a Fragment.

  2. Ignore Keys in Lists: Don’t forget to use keys with Fragments when mapping over arrays to create lists. This is crucial for React’s re-rendering efficiency.

  3. Complicate Simple Structures: If a single wrapping element suffices and does not complicate the DOM structure (like a single <div>), there’s no need to use a Fragment.

Common Pitfalls and How to Avoid Them

  1. Misunderstanding When to Use Fragments: A common mistake is using them unnecessarily or not using them when they could simplify the component structure. Understanding the specific use cases, like avoiding extra nodes or grouping list items, helps avoid this pitfall.

  2. Forgetting to Use Keys in Iterable Elements: When using Fragments in a map function, it’s essential to provide a unique key to each Fragment. Omitting keys can lead to issues with React’s rendering process, affecting performance and causing bugs.

  3. Overlooking Browser Tools for Debugging: Sometimes, developers may not use browser development tools to inspect the DOM. Using these tools can reveal how Fragments affect the DOM structure and help identify unnecessary nesting.

  4. Ignoring Code Readability: While Fragments make the DOM structure cleaner, they can sometimes make the JSX code harder to read, especially when overused. Balancing the use of Fragments to keep both the code and the DOM readable is key.

  5. Confusion Between Short and Long Syntax: New developers might get confused between the short (<> </>) and long (<React.Fragment></React.Fragment>) syntax. Remember that the short syntax is for simple groupings without keys, while the long syntax should be used when keys are necessary.

Frequently Asked Questions

Below, we’ve answered some top questions about using Fragments in React.

Can you return multiple elements in React without a Fragment?

Yes, you can return multiple elements without using a Fragment by enclosing them in an array and using commas to separate the elements. However, you must provide a unique key prop to each element in the array.

Do React Fragments affect the lifecycle methods or state of a component?

No, React Fragments do not affect lifecycle methods or the state of a component. They are primarily a tool for grouping elements without adding extra nodes to the DOM and do not impact component behavior.

Can you style React fragments?

No, React Fragments are not real DOM elements; they are purely syntactical tools in React for grouping components. As such, they cannot be styled directly. Any styling needs to be applied to actual DOM elements within the Fragment.

How do Fragments differ from other wrapper elements like divs?

Unlike <div> or other wrapper elements, Fragments do not create an additional DOM node. This is beneficial for maintaining a cleaner DOM structure and can be crucial in certain contexts (like within a table) where additional wrapper elements would disrupt the layout.

Can you give a fragment a key in React?

Yes, you can give a key to a React Fragment, but this is only possible with the long syntax (<React.Fragment key={…}>). The short syntax for declaring fragments (<> </>) does not support keys.

What are the benefits of using React fragments?

The main benefits of using React Fragments include:

  • Avoiding extra nodes in the DOM, which can improve performance and make the DOM cleaner.

  • Preserving the correct structure of HTML in certain contexts (like tables) where additional divs would be inappropriate.

What is the difference between view and fragment in React?

In React, the term “view” typically refers to a component or a part of the UI. Fragment, conversely, is a specific feature for grouping children elements without adding extra nodes to the DOM. “View” is a broader term, often representing a complete UI piece, while “Fragment” is a tool used in these views’ rendering process.

Final Thoughts on React Fragments

Fragments in React are essential for grouping JSX expressions while maintaining the component’s layout. This is beneficial to React developers as it encourages clean and maintainable code.

In this tutorial, we explained the benefits of using the React fragment component as well as when to use the shorthand syntax over the long syntax. Knowledge of this should help you write cleaner codes with minimal performance issues.

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Additional Resources

If you enjoyed reading this article, check out other articles from our blog to improve your React knowledge:

David Ozokoye

David Ozokoye

Software Engineer and Technical Writer