A simple and beautiful text diff viewer component made with Diff and React.

Inspired by the Github diff viewer, it includes features like split view, inline view, word diff, line highlight and more. It is highly customizable and it supports almost all languages.

Most credit goes to Pranesh Ravi who created the original diff viewer. I've just made a few modifications and updated the dependencies so they work with modern stacks.

Install

yarn add react-diff-viewer-continued

# or

npm i react-diff-viewer-continued

# or

pnpm add react-diff-viewer-continued

Usage

import React, { PureComponent } from 'react';
import ReactDiffViewer from 'react-diff-viewer-continued';

const oldCode = `
const a = 10
const b = 10
const c = () => console.log('foo')

if(a > 10) {
  console.log('bar')
}

console.log('done')
`;
const newCode = `
const a = 10
const boo = 10

if(a === 10) {
  console.log('bar')
}
`;

class Diff extends PureComponent {
  render = () => {
    return (
      <ReactDiffViewer oldValue={oldCode} newValue={newCode} splitView={true} />
    );
  };
}

Props

Instance Methods

resetCodeBlocks() - Resets the expanded code blocks to its initial state. Returns true on successful reset and false during unsuccessful reset.

Large Diffs and Performance

For large files (thousands of lines), the diff viewer provides several features to maintain good performance:

Virtualization with infiniteLoading

Enable virtualization to only render visible rows:

<ReactDiffViewer
  oldValue={largeOldFile}
  newValue={largeNewFile}
  infiniteLoading={{
    pageSize: 20,
    containerHeight: '80vh'
  }}
  loadingElement={() => (
    <div style={{ padding: '20px', textAlign: 'center' }}>
      Computing diff...
    </div>
  )}
/>

When infiniteLoading is enabled:

• Only visible rows are rendered (virtualization)
• Word-level diffs are computed on-demand as lines become visible
• A loading element can be shown while the initial diff is computed

Use optimized diff methods for structured data

For JSON and YAML files, always use the dedicated diff methods:

// For JSON files - up to 100x faster for large files
<ReactDiffViewer
  oldValue={jsonObject}
  newValue={newJsonObject}
  compareMethod={DiffMethod.JSON}
/>

// For YAML files
<ReactDiffViewer
  oldValue={yamlString}
  newValue={newYamlString}
  compareMethod={DiffMethod.YAML}
/>

See JSON and YAML diffing for more details.

Syntax Highlighting

Syntax highlighting is a bit tricky when combined with diff. Here, React Diff Viewer provides a simple render prop API to handle syntax highlighting. Use renderContent(content: string) => JSX.Element and your favorite syntax highlighting library to achieve this.

An example using Prism JS

// Load Prism CSS
<link
  href="https://cdnjs.cloudflare.com/ajax/libs/prism/1.15.0/prism.min.css"
/>

// Load Prism JS
<script src="https://cdnjs.cloudflare.com/ajax/libs/prism/1.15.0/prism.min.js"></script>

import React, { PureComponent } from 'react';
import ReactDiffViewer from 'react-diff-viewer-continued';

const oldCode = `
const a = 10
const b = 10
const c = () => console.log('foo')

if(a > 10) {
  console.log('bar')
}

console.log('done')
`;
const newCode = `
const a = 10
const boo = 10

if(a === 10) {
  console.log('bar')
}
`;

class Diff extends PureComponent {
  highlightSyntax = (str) => (
    <pre
      style={{ display: 'inline' }}
      dangerouslySetInnerHTML={{
        __html: Prism.highlight(str, Prism.languages.javascript),
      }}
    />
  );

  render = () => {
    return (
      <ReactDiffViewer
        oldValue={oldCode}
        newValue={newCode}
        splitView={true}
        renderContent={this.highlightSyntax}
      />
    );
  };
}

Text block diff comparison

Different styles of text block diffing are possible by using the enums corresponding to various JsDiff methods (learn more). The supported methods are as follows.

enum DiffMethod {
  CHARS = 'diffChars',
  WORDS = 'diffWords',
  WORDS_WITH_SPACE = 'diffWordsWithSpace',
  LINES = 'diffLines',
  TRIMMED_LINES = 'diffTrimmedLines',
  SENTENCES = 'diffSentences',
  CSS = 'diffCss',
  JSON = 'diffJson',  // Optimized for JSON files
  YAML = 'diffYaml',  // Optimized for YAML files
}

JSON and YAML diffing

For JSON and YAML files, use the dedicated DiffMethod.JSON and DiffMethod.YAML methods. These use an optimized structural comparison algorithm that is significantly faster than generic text diff for large files.

Why use these methods?

Generic text diff algorithms (like CHARS or WORDS) compare files character-by-character using the Myers diff algorithm, which has O(ND) complexity where N is the file size and D is the number of differences. For large JSON/YAML files (thousands of lines), this can take several seconds or even freeze the browser.

The JSON and YAML methods instead:

1. Parse the data structure
2. Compare objects/arrays structurally
3. Only run text diff on the parts that actually differ

This reduces comparison time from seconds to milliseconds for typical configuration files.

import React from 'react';
import ReactDiffViewer, { DiffMethod } from 'react-diff-viewer-continued';

// For JSON - can pass objects directly
const oldJson = { name: "Original", items: [1, 2, 3] };
const newJson = { name: "Updated", items: [1, 2, 3, 4] };

// For YAML - pass as strings
const oldYaml = `
name: Original
items:
  - 1
  - 2
`;
const newYaml = `
name: Updated
items:
  - 1
  - 2
  - 3
`;

function JsonDiff() {
  return (
    <ReactDiffViewer
      oldValue={oldJson}
      newValue={newJson}
      compareMethod={DiffMethod.JSON}
      splitView={true}
    />
  );
}

function YamlDiff() {
  return (
    <ReactDiffViewer
      oldValue={oldYaml}
      newValue={newYaml}
      compareMethod={DiffMethod.YAML}
      splitView={true}
    />
  );
}

Other diff methods

For regular code or text files, use the standard diff methods:

import React, { PureComponent } from 'react';
import ReactDiffViewer, { DiffMethod } from 'react-diff-viewer-continued';

const oldCode = `
const a = 10
const b = 10
`;
const newCode = `
const a = 10
const boo = 10
`;

class Diff extends PureComponent {
  render = () => {
    return (
      <ReactDiffViewer
        oldValue={oldCode}
        newValue={newCode}
        compareMethod={DiffMethod.WORDS}
        splitView={true}
      />
    );
  };
}

Overriding Styles

React Diff Viewer uses emotion for styling. It also offers a simple way to override styles and style variables. You can supply different variables for both light and dark themes. Styles will be common for both themes.

Below are the default style variables and style object keys.

// Default variables and style keys

const defaultStyles = {
  variables: {
    light: {
      diffViewerBackground: '#fff',
      diffViewerColor: '#212529',
      addedBackground: '#e6ffed',
      addedColor: '#24292e',
      removedBackground: '#ffeef0',
      removedColor: '#24292e',
      wordAddedBackground: '#acf2bd',
      wordRemovedBackground: '#fdb8c0',
      addedGutterBackground: '#cdffd8',
      removedGutterBackground: '#ffdce0',
      gutterBackground: '#f7f7f7',
      gutterBackgroundDark: '#f3f1f1',
      highlightBackground: '#fffbdd',
      highlightGutterBackground: '#fff5b1',
      codeFoldGutterBackground: '#dbedff',
      codeFoldBackground: '#f1f8ff',
      emptyLineBackground: '#fafbfc',
      gutterColor: '#212529',
      addedGutterColor: '#212529',
      removedGutterColor: '#212529',
      codeFoldContentColor: '#212529',
      diffViewerTitleBackground: '#fafbfc',
      diffViewerTitleColor: '#212529',
      diffViewerTitleBorderColor: '#eee',
    },
    dark: {
      diffViewerBackground: '#2e303c',
      diffViewerColor: '#FFF',
      addedBackground: '#044B53',
      addedColor: 'white',
      removedBackground: '#632F34',
      removedColor: 'white',
      wordAddedBackground: '#055d67',
      wordRemovedBackground: '#7d383f',
      addedGutterBackground: '#034148',
      removedGutterBackground: '#632b30',
      gutterBackground: '#2c2f3a',
      gutterBackgroundDark: '#262933',
      highlightBackground: '#2a3967',
      highlightGutterBackground: '#2d4077',
      codeFoldGutterBackground: '#21232b',
      codeFoldBackground: '#262831',
      emptyLineBackground: '#363946',
      gutterColor: '#464c67',
      addedGutterColor: '#8c8c8c',
      removedGutterColor: '#8c8c8c',
      codeFoldContentColor: '#555a7b',
      diffViewerTitleBackground: '#2f323e',
      diffViewerTitleColor: '#555a7b',
      diffViewerTitleBorderColor: '#353846',
    }
  },
  diffContainer?: {}, // style object
  diffRemoved?: {}, // style object
  diffAdded?: {}, // style object
  marker?: {}, // style object
  emptyGutter?: {}, // style object
  highlightedLine?: {}, // style object
  lineNumber?: {}, // style object
  highlightedGutter?: {}, // style object
  contentText?: {}, // style object
  gutter?: {}, // style object
  line?: {}, // style object
  wordDiff?: {}, // style object
  wordAdded?: {}, // style object
  wordRemoved?: {}, // style object
  codeFoldGutter?: {}, // style object
  codeFold?: {}, // style object
  emptyLine?: {}, // style object
  content?: {}, // style object
  titleBlock?: {}, // style object
  splitView?: {}, // style object
}

To override any style, just pass the new style object to the styles prop. New style will be computed using Object.assign(default, override).

For keys other than variables, the value can either be an object or string interpolation.

import React, { PureComponent } from 'react';
import ReactDiffViewer from 'react-diff-viewer-continued';

const oldCode = `
const a = 10
const b = 10
const c = () => console.log('foo')

if(a > 10) {
  console.log('bar')
}

console.log('done')
`;
const newCode = `
const a = 10
const boo = 10

if(a === 10) {
  console.log('bar')
}
`;

class Diff extends PureComponent {
  highlightSyntax = (str) => (
    <span
      style={{ display: 'inline' }}
      dangerouslySetInnerHTML={{
        __html: Prism.highlight(str, Prism.languages.javascript),
      }}
    />
  );

  render = () => {
    const newStyles = {
      variables: {
        dark: {
          highlightBackground: '#fefed5',
          highlightGutterBackground: '#ffcd3c',
        },
      },
      line: {
        padding: '10px 2px',
        '&:hover': {
          background: '#a26ea1',
        },
      },
    };

    return (
      <ReactDiffViewer
        styles={newStyles}
        oldValue={oldCode}
        newValue={newCode}
        splitView={true}
        renderContent={this.highlightSyntax}
      />
    );
  };
}

Local Development

pnpm install
pnpm build # or use yarn build:watch
pnpm start:examples

Check package.json for more build scripts.

Contributors

Eric M. 💻

Andrei Kovalevsky 💻

Chang Hyun Kim 💻

License

MIT