A leaner and meaner implementation of JSON-Patch. Small footprint. High performance. Also support dual directions! I.e. you can both apply patches and generate patches.

JSON-Patch (RFC6902) is a new standard format that allows you to update a JSON document by sending the changes rather than the whole document. JSON Patch plays well with the HTTP PATCH verb (method) and REST style programming.

Mark Nottingham has a nice blog about it.

0.5 KB minified and gzipped (1.1 KB minified)

• Allows you to apply patches on object trees for incoming traffic.
• Allows you to freely manipulate object trees and then generate patches for outgoing traffic.
• ES6/7 Object.observe() is used when available.
• Tested in IE 8-10, Firefox, Chrome and Node.js

• A /bin directory will be added with minified versions
• More unit tests

Include json-patch.js if you want support for applying patches or include json-patch-duplex.js if you also want to generate patches.

Install the current version (and save it as a dependency in package.json):

$ npm install fast-json-patch --save

Call require to get the instance:

var jsonpatch = require('fast-json-patch')

Applying patches:

var myobj = { firstName:"Albert", contactDetails: { phoneNumbers: [ ] } };
var patches = [
   {op:"replace", path:"/firstName", value:"Joachim" },
   {op:"add", path:"/lastName", value:"Wester" },
   {op:"add", path:"/contactDetails/phoneNumbers/0", value:{ number:"555-123" }  }
   ];
jsonpatch.apply( myobj, patches );
// myobj == { firstName:"Joachim", lastName:"Wester", contactDetails:{ phoneNumbers[ {number:"555-123"} ] } };

Generating patches:

var myobj = { firstName:"Joachim", lastName:"Wester", contactDetails: { phoneNumbers: [ { number:"555-123" }] } };
observer = jsonpatch.observe( myobj );
myobj.firstName = "Albert";
myobj.contactDetails.phoneNumbers[0].number = "123";
myobj.contactDetails.phoneNumbers.push({number:"456"});
var patches = jsonpatch.generate(observer);
// patches  == [
//   { op:"replace", path="/firstName", value:"Albert"},
//   { op:"replace", path="/contactDetails/phoneNumbers/0/number", value:"123"},
//   { op:"add", path="/contactDetails/phoneNumbers/1", value:{number:"456"}}];

1. Testing json-patch.js

• Load src/patchtest.html in your web browser

2. Testing json-patch-duplex.js

• Load src/test-duplex.html in your web browser

Each of the test suite files contains Jasmine unit test suite and JSLitmus performance test suite.

To run JSLitmus performance tests, press "Run Tests" button.

1. Go to directory where you have cloned the repo
2. Install Jasmine Node.js module by running command npm install jasmine-node -g
3. Testing json-patch.js

• Run command jasmine-node --matchall --config duplex no src/test.js

4. Testing json-patch-duplex.js

• Run command jasmine-node --matchall --config duplex yes src/test.js src/test-duplex.js