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

Inspired from 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.

Check here for v2.0

Install

``bash
yarn add react-diff-viewer

or

npm i react-diff-viewer
`

Usage

`javascript
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 (

);
};
}
`

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 | DiffMethod | DiffMethod.CHARS | JsDiff text diff method used for diffing strings. Check out the guide to use different methods. |
| 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. |
| classes | object | {} | To override styles. Learn more about overriding styles |
| leftTitle | string | undefined | Column title for left section of the diff in split view. This will be used as the only title in inline view. |
| rightTitle | string | undefined | Column title for right section of the diff in split view. This will be ignored in inline view. |
| linesOffset | number | 0 | Number to start count code lines from. |

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 achieve this.

An example using Prism JS

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

// Load Prism JS

`

`javascript
import React, { PureComponent } from 'react';
import ReactDiffViewer from 'react-diff-viewer';
import 'react-diff-viewer/lib/light.css';

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 => (
style={{ display: 'inline' }}
dangerouslySetInnerHTML={{
__html: Prism.highlight(str, Prism.languages.javascript),
}}
/>
);

render = () => {
return (
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 variou JsDiff methods (learn more). The supported methods are as follows.

`javascript
enum DiffMethod {
CHARS = 'diffChars',
WORDS = 'diffWords',
WORDS_WITH_SPACE = 'diffWordsWithSpace',
LINES = 'diffLines',
TRIMMED_LINES = 'diffTrimmedLines',
SENTENCES = 'diffSentences',
CSS = 'diffCss',
}
`

`javascript
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 (
oldValue={oldCode}
newValue={newCode}
compareMethod={DiffMethod.WORDS}
splitView={true}
/>
);
};
}
`

Overriding Styles

React Diff Viewer uses css for styling. It also offers a simple way to override styles. You can supply different class names.

Below are the default class object keys.

`javascript

// Default style keys

const defaultClasses = {
diffContainer?: 'react-diff-viewer',
diffRemoved?: 'react-diff-viewer__line-cell--diff-removed',
diffAdded?: 'react-diff-viewer__line-cell--diff-added',
marker?: 'react-diff-viewer__marker',
emptyGutter?: 'react-diff-viewer__gutter--empty',
highlightedLine?: 'react-diff-viewer__line-cell--highlight',
lineNumber?: 'react-diff-viewer__line-number',
highlightedGutter?: 'react-diff-viewer__gutter--highlight',
contentText?: 'react-diff-viewer__content-text',
gutter?: 'react-diff-viewer__gutter',
line?: 'react-diff-viewer__line',
wordDiff?: 'react-diff-viewer__word-diff',
wordAdded?: 'react-diff-viewer__word-diff--word-added',
wordRemoved?: 'react-diff-viewer__word-diff--word-removed',
codeFoldGutter?: 'react-diff-viewer__code-fold-gutter',
codeFold?: 'react-diff-viewer__code-fold',
emptyLine?: 'react-diff-viewer__line-cell--empty',
content?: 'react-diff-viewer__content',
titleBlock?: 'react-diff-viewer__title-block',
splitView?: 'react-diff-viewer--split-view',
}
`

To override any style, just pass the class names to the classes prop.

`css
/ styles.css /
.diff-viewer__line {
padding: 10px 2px;
}

.diff-viewer__line:hover {
background: #a26ea1;
}
`

`javascript
import React, { PureComponent } from 'react';
import ReactDiffViewer from 'react-diff-viewer';
import './styles.css'

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 => (
style={{ display: 'inline' }}
dangerouslySetInnerHTML={{
__html: Prism.highlight(str, Prism.languages.javascript),
}}
/>
);

render = () => {
const classes = {
line: 'diff-viewer__line',
};

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

Local Development

`bash
yarn install
yarn build # or use yarn build:watch
yarn start:examples
``

Check package.json for more build scripts.

License

MIT