[](https://travis-ci.com/praneshr/react-diff-viewer)
[](https://badge.fury.io/js/%40chunxei%2Freact-diff-viewer)
[](https://github.com/chunxei/react-diff-viewer/blob/master/LICENSE)
**NOTE: This is a fork of Pranesh Ravi's [react-diff-viewer](https://github.com/praneshr/react-diff-viewer) with added hooks and features that allow for more fluid multilline selection and enable commenting.**
A simple and beautiful text diff viewer component made with [Diff](https://github.com/kpdecker/jsdiff) and [React](https://reactjs.org).
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.
## Install
```bash
yarn add @chunxei/react-diff-viewer
# or
npm i @chunxei/react-diff-viewer
```
## Usage
```javascript
import React, { PureComponent } from 'react';
import ReactDiffViewer from '@chunxei/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 (
);
};
}
```
## Preview
## 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](https://github.com/praneshr/react-diff-viewer/tree/v3.0.0#text-block-diff-comparison) to use different methods. |
| hideLineNumbers | `boolean` | `false` | Show and hide line numbers. |
| canSelectLines | `interface { L: boolean; R: boolean }` | `{ L: true, R: true }` | Enable and disable line select for each side. |
| renderContent | `function` | `undefined` | Render Prop API to render code in the diff viewer. Helpful for [syntax highlighting](#syntax-highlighting) |
| onLineNumberClick | `function` | `undefined` | Event handler for line number click. `(lineId: string, isNewSelection: boolean) => void`. `isNewSelection` evaluates to `false` if the `lineId` is already present in `highlightLines`, and true otherwise. |
| 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](#overriding-styles) |
| useDarkTheme | `boolean` | `true` | To enable/disable dark theme. |
| 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. |
### Added from v3.2.0
| Prop | Type | Default | Description |
| ------------------------- | --------------- | ------------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| onHighlightLines | `function` | `undefined` | `(highlightedLines: string[], prefix: string) => void`. Event handler triggered when lines are highlighted in a batch, such as when a comment that references a set of lines is clicked. |
| onClearHighlights | `function` | `undefined` | `() => void`. Event handler for when the clear button is clicked. Expected to trigger a wipe for `highlightLines`. |
| comments* | `{ L: array[object]; R: array[object] }` | `{ L: [], R: [] }` | Comments for the respective panels. Each comment object must contain a `commentLines: string[]` field that holds the line ids of the lines the comment is for, a `commentLabel: string` field holding the label to be displayed on the comment button, and a `isUrgent: boolean` field to style the button with the `_urgent` class. |
| onCommentClick* | `function` | `undefined` | `(comment: Record, commentLines: string[], prefix: string) => void`. Event handler for comment click. |
| onAddNewCommentStart* | `function` | `undefined` | `(selectedLines: string[], prefix: string) => void`. Returns a function with highlighted lines in the closure. |
## 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](https://prismjs.com)
```html
// Load Prism CSS
// Load Prism JS
```
```javascript
import React, { PureComponent } from 'react';
import ReactDiffViewer from '@chunxei/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 => (
);
render = () => {
return (
);
};
}
```
## Text block diff comparison
Different styles of text block diffing are possible by using the enums corresponding to variou JsDiff methods ([learn more](https://github.com/kpdecker/jsdiff/tree/v4.0.1#api)). 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 '@chunxei/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 (
);
};
}
```
## Overriding Styles
React Diff Viewer uses [emotion](https://emotion.sh/) 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.
```javascript
// 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
// Added from v3.2.0
highlightActionButtons?: {}, // style object
lineSelectButton?: {}, // style object
addCommentButton?: {}, // style object
clearHighlightButton?: {}, // style object
commentActionButtons?: {}, // style object
viewCommentButton?: {}, // 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.
```javascript
import React, { PureComponent } from 'react';
import ReactDiffViewer from '@chunxei/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 => (
);
render = () => {
const newStyles = {
variables: {
dark: {
highlightBackground: '#fefed5',
highlightGutterBackground: '#ffcd3c',
},
},
line: {
padding: '10px 2px',
'&:hover': {
background: '#a26ea1',
},
},
};
return (
);
};
}
```
## Local Development
```bash
yarn install
yarn build # or use yarn build:watch
yarn start:examples
# to test in isolation using storybook
yarn sb
```
Check package.json for more build scripts.
## License
MIT
---
_Source: https://npm.io/package/@chunxei/react-diff-viewer · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._
