Package ships both CommonJs .cjs for use with require and EsModule .mjs for use with import.

Install

npm install get-json-patches

How To Use

import getJsonPatches from 'get-json-patches';

const obj1 = { s: 'string', n: 345.21, b: true, o: {s: 'string'}, a: [1,2,3]}
const obj2 = { s: 'string', n: 345.64, b: false, o: {s: 'new'}, a: [1,2], aNew: 'new prop'}

const patches = getJsonPatches(obj1, obj2);
/*
patches =
[
    {"op":"replace","path":"/n","value":345.64},
    {"op":"replace","path":"/b","value":false},
    {"op":"replace","path":"/o/s","value":"new"},
    {"op":"replace","path":"/a","value":[1,2]},
    {"op":"add","path":"/aNew","value":"new prop"}
]
*/

For additional use case scenarios you can look over the unit tests.

Motivation

I needed a simple way to generate a list of patch objects from comparing 2 javascript objects. Preferably to use in the browser on the client machine to prevent having to send a complete json object to a server for comparison and then to a db or api to apply partial updates. There are many javascript libraries that implement json patch, many of which are listed at jsonpatch.com. Some existing libraries offer a diff function to construct collection of patch objects but this seams like a additional after thought to many libs and therefore they are large libs that implement all parts of the json patch spec. Many API's including Azure Cosmos Db expect a json patch and can implement partial updates. This lib just does object comparison and patch creation.

TODO List

• [X] Implement replace primitives
• [X] Implement replace objects
• [X] Implement replace arrays
• [X] Implement add object
• [X] Implement add arrays
• [ ] Add RFC spec path substitutes
• [ ] Implement remove in array
• [ ] Implement append to array with - in path

• Currently the array functionality will just replace entire array if array lengths differ and will only iterate array when lengths are the same.

• [ ] rfc6901 pointer should be '' rather then '/' to point at root

Notes

For array comparisons the length of the arrays are compared first and if different then the entire array is replaced at the path. If array lengths are the same, we loop over the array comparing the value at same index from first array with second array. If values are different then a set op patch will be returned at /arrayPath/<index> path.