JSON Merge Patch

An implementation of the JSON Merge Patch RFC 7396

JSON Merge Patch (RFC 7396) is a standard format that allows you to update a JSON document by sending the changes rather than the whole document. JSON Merge Patch plays well with the HTTP PATCH verb (method) and REST style programming.

Install

Install the current version (and save it as a dependency):

npm

$ npm install json-merge-patch --save

Usage

Applying patches:

jsonmergepatch.apply(obj: Object, patch: Object) : Object

Applies patch onto source obj.

Example:

var source = {
  "title": "Goodbye!",
  "author" : {
		"givenName" : "John",
		"familyName" : "Doe"
	}
};

var patch = {
	"title": 'Hello!',
	"author": {
		"familyName": null
	}
}

var target = jsonmergepatch.apply(source, patch);

// target = {
// 	"title": "Hello!",
//   "author" : {
// 		"givenName" : "John",
// 	}
// }

Generating patches:

jsonmergepatch.generate(source: Object, target: Object) : Object

Compares source and target object and generates a patch of the changes necessary to convert source into target.

Example:

var source = {
  "title": "Goodbye!",
  "author" : "John Doe"
};

var target = {
	"title": "Hello!",
};

var patch = jsonmergepatch.generate(source, target);

// patch = {
// 	"title": 'Hello!',
// 	"author": null
// }

Merging patches

This function is outside the scope of the RFC, its purpose is to combine/squash successive patches of the same entity into one patch. Use it at your own risks.

Usage with Javascript objects

This library is primarily designed to work with JSON. Nonetheless, it is possible to use Javascript objects if the method toJSON() is implemented, the library will then serialize your object using it.

var patch = jsonmergepatch.generate(
  {
    "title": "Goodbye!"
  },
  {
    toJSON: () {
      return {
        "title": "I am serialized"
      }
    },
  }
);
// patch = {
// 	"title": "I am serialized",
// }

var patch = jsonmergepatch.generate(
  {},
  {
    date: new Date("2020-05-09T00:00:00.000")
  }
);
// patch = {
// 	date: "2020-05-09T00:00:00.000"
// }

Running tests

npm test

License

MIT