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

Hello! v3.0 is on the way. I'm expecting to release it sometime next week.





React Diff Viewer





Build Status npm version GitHub license

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

Inspired from Github's 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. Check out the demo.

Check here for v1.0

Install

yarn add react-diff-viewer

# or

npm i react-diff-viewer

Usage

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

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

Prop Type Default Description
oldValue string '' Old value as string.
newValue string '' New value as string.
splitView boolean true Switch between unified and split view.
disableWordDiff boolean false Show and hide word diff in a diff line.
compareMethod string 'diffChars' JsDiff text diff method from https://github.com/kpdecker/jsdiff/tree/v4.0.1#api
hideLineNumbers boolean false Show and hide line numbers.
renderContent function undefined Render Prop API to render code in the diff viewer. Helpful for syntax highlighting
onLineNumberClick function undefined Event handler for line number click. (lineId: string) => void
highlightLines array[string] [] List of lines to be highlighted. Works together with onLineNumberClick. Line number are prefixed with L and R for the left and right section of the diff viewer, respectively. For example, L-20 means 20th line in the left pane. To highlight a range of line numbers, pass the prefixed line number as an array. For example, [L-2, L-3, L-4, L-5] will highlight the lines 2-5 in the left pane.
showDiffOnly boolean true Shows only the diffed lines and folds the unchanged lines
extraLinesSurroundingDiff number 3 Number of extra unchanged lines surrounding the diff. Works along with showDiffOnly.
codeFoldMessageRenderer function Expand {number} of lines ... Render Prop API to render code fold message.
styles object {} To override style variables and styles. Learn more about overriding styles

Instance Methods

resetCodeBlocks() - Resets the expanded code blocks to it's initial state. Return true on successful reset and false during unsuccessful reset.

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 acheive 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'

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 v4.0.1 JsDiff text block method names (learn more).

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

const oldCode = `
{
  "name": "Original name",
  "description": null
}
`
const newCode = `
{
  "name": "My updated name",
  "description": "Brand new description",
  "status": "running"
}
`

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

Overriding Styles

React Diff Viewer uses emotion for styling. It also offers a simple way to override styles and style variables.

Below are the default style variables and style object keys.

// Default variables and style keys

const defaultStyles = {
  variables: {
    diffViewerBackground: '#fff',
    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',
  },
  diffContainer?: {}, //style object
  diffRemoved?: {}, //style object
  diffAdded?: {}, //style object
  marker?: {}, //style object
  highlightedLine?: {}, //style object
  highlightedGutter?: {}, //style object
  gutter?: {}, //style object
  line?: {}, //style object
  wordDiff?: {}, //style object
  wordAdded?: {}, //style object
  wordRemoved?: {}, //style object
  codeFoldGutter?: {}, //style object
  emptyLine?: {}, //style object
  emptyGutter?: {}, //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'

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: {
        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

yarn install
yarn build # or use yarn build:watch
yarn start:exmaples

Check package.json for more build scripts.

License

MIT

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