alexturpin / json-diff-kit

A better JSON differ & viewer, support LCS diff for arrays and recognise some changes as "modification" apart from simple "remove"+"add".

JSON Diff Kit

A better JSON differ & viewer library written in TypeScript. DEMO here!

Notice: considering most of the browsers now support ES6, this library has only the ES6 version. If you need the compatibility with older browsers, please configure the compiler in your project (e.g. add this library to the include field in babel.config.js).

Install

You can install json-diff-kit via various package managers.

# using npm
npm i json-diff-kit --save

# using yarn
yarn add json-diff-kit

# using pnpm
pnpm add json-diff-kit

Quick Start

To generate the diff data:

import { Differ } from 'json-diff-kit';

// the two JS objects
const before = {
  a: 1,
  b: 2,
  d: [1, 5, 4],
  e: ['1', 2, { f: 3, g: null, h: [5], i: [] }, 9],
  m: [],
  q: 'JSON diff can\'t be possible',
  r: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.',
  s: 1024,
};
const after = {
  b: 2,
  c: 3,
  d: [1, 3, 4, 6],
  e: ['1', 2, 3, { f: 4, g: false, i: [7, 8] }, 10],
  j: { k: 11, l: 12 },
  m: [
    { n: 1, o: 2 },
    { p: 3 },
  ],
  q: 'JSON diff is possible!',
  r: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed quasi architecto beatae incididunt ut labore et dolore magna aliqua.',
  s: '1024',
};

// all configs are optional
const differ = new Differ({
  detectCircular: true,    // default `true`
  maxDepth: Infinity,      // default `Infinity`
  showModifications: true, // default `true`
  arrayDiffMethod: 'lcs',  // default `"normal"`, but `"lcs"` may be more useful
});

// you may want to use `useMemo` (for React) or `computed` (for Vue)
// to avoid redundant computations
const diff = differ.diff(before, after);
console.log(diff);

You can use your own component to visualize the diff data, or use the built-in viewer:

import { Viewer } from 'json-diff-kit';
import type { DiffResult } from 'json-diff-kit';

import 'json-diff-kit/dist/viewer.css';

interface PageProps {
  diff: [DiffResult[], DiffResult[]];
}

const Page: React.FC<PageProps> = props => {
  return (
    <Viewer
      diff={props.diff}          // required
      indent={4}                 // default `2`
      lineNumbers={true}         // default `false`
      highlightInlineDiff={true} // default `false`
      inlineDiffOptions={{
        mode: 'word',            // default `"char"`, but `"word"` may be more useful
        wordSeparator: ' ',      // default `""`, but `" "` is more useful for sentences
      }}
    />
  );
};

The result is here:

More Complex Usages

Please check the demo page, where you can adjust nearly all parameters and see the result.

Algorithm Details

Please refer to the article JSON Diff Kit: A Combination of Several Simple Algorithms.

Features & Roadmap

• Provide a Differ class and a Viewer component
• Merge "remove & add" at the same place as a modification
• Support inline diffing by word instead of by character
• Generate code directly in the demo page
• Add CLI tool
• Improve unit tests

License

MIT