JSON structural diff

Does exactly what you think it does:

Installation

npm install json-diff

Usage

Simple:

json-diff a.json b.json

Detailed:

% json-diff --help
Usage: json-diff [-vjC] first.json second.json

Arguments:
  first.json            Old file
  second.json           New file

General options:
  -v, --verbose         Output progress info
  -C, --[no-]color      Colored output
  -j, --raw-json        Display raw JSON encoding of the diff
  -h, --help            Display this usage information

Features

• colorized, diff-like output
• fuzzy matching of modified array elements (when array elements are object hierarchies)
• reasonable test coverage (far from 100%, though)

Tests

Run:

npm test

Test coverage report:

npm run-script cov

Output:

colorize
  ✓ should return ' <value>' for a scalar value
  ✓ should return '-<old value>', '+<new value>' for a scalar diff
  ✓ should return '-<removed key>: <removed value>' for an object diff with a removed key
  ✓ should return '+<added key>: <added value>' for an object diff with an added key
  ✓ should return '+<added key>: <added stringified value>' for an object diff with an added key and a non-scalar value
  ✓ should return ' <modified key>: <colorized diff>' for an object diff with a modified key
  ✓ should return '+<inserted item>' for an array diff
  ✓ should return '-<deleted item>' for an array diff

diff
  with simple scalar values
    ✓ should return undefined for two identical numbers
    ✓ should return undefined for two identical strings
    ✓ should return { __old: <old value>, __new: <new value> } object for two different numbers
  with objects
    ✓ should return undefined for two objects with identical contents
    ✓ should return undefined for two object hierarchies with identical contents
    ✓ should return { <key>__deleted: <old value> } when the second object is missing a key
    ✓ should return { <key>__added: <new value> } when the first object is missing a key
    ✓ should return { <key>: { __old: <old value>, __new: <new value> } } for two objects with diffent scalar values for a key
    ✓ should return { <key>: <diff> } with a recursive diff for two objects with diffent values for a key
  with arrays of scalars
    ✓ should return undefined for two arrays with identical contents
    ✓ should return [..., ['-', <removed item>], ...] for two arrays when the second array is missing a value
    ✓ should return [..., ['+', <added item>], ...] for two arrays when the second one has an extra value
    ✓ should return [..., ['+', <added item>]] for two arrays when the second one has an extra value at the end (edge case test)
  with arrays of objects
    ✓ should return undefined for two arrays with identical contents
    ✓ should return [..., ['-', <removed item>], ...] for two arrays when the second array is missing a value
    ✓ should return [..., ['+', <added item>], ...] for two arrays when the second array has an extra value
    ✓ should return [..., ['~', <diff>], ...] for two arrays when an item has been modified (note: involves a crazy heuristic)

✔ 25 tests complete (12ms)

License

© Andrey Tarantsov. Distributed under the MIT license.