json-patch-lite

Minimal RFC 6902 JSON Patch: apply add/remove/replace/move/copy/test operations, and generate a patch between two plain objects. Zero dependencies.

Install

npm install json-patch-lite

Quick start

import { applyPatch, generatePatch } from 'json-patch-lite';

const doc = { name: 'Tejas', role: 'engineer' };
const patched = applyPatch(doc, [{ op: 'replace', path: '/role', value: 'architect' }]);

const patch = generatePatch(oldConfig, newConfig);
// send `patch` over the wire instead of the whole document

Why this exists

Sending full documents on every update wastes bandwidth and makes it hard to reason about what actually changed. JSON Patch (RFC 6902) is the standard, minimal wire format for "here's exactly what changed" — this package covers applying patches and generating them from a before/after pair, without pulling in a general-purpose diff library.

API

• applyPatch(doc, patch) — returns a new document with the patch applied (does not mutate doc)
• generatePatch(from, to) — returns the minimal add/remove/replace ops turning from into to

generatePatch does object-tree diffing only (no move/copy detection or array-element diffing) — arrays that differ are replaced wholesale, which keeps the diff logic small and predictable.

License

MIT