Patching

Generate RFC 6902 JSON Patch operations and apply them to targets.

Previous: Diffing · Next: Serialization

Playground

Open Patch explorer → — generate ops from a diff and apply them interactively.

Problem → approach

Typical pain	Patch pipeline
Sending full object snapshots over the wire on every edit	patch(diffResult) → compact add / remove / replace ops
Mutating shared state when applying updates	applyPatch() returns a new object; clone the target when you need the original
Undo/redo requires storing full before/after copies	revertPatch(operations) generates inverse ops for a stack

Generate patch

import { diff, patch } from "@jayoncode/object-diff";

const result = diff(before, after);
const operations = patch(result);
// [{ op: "replace", path: "/name", value: "Jane" }, ...]

Apply patch

import { applyPatch } from "@jayoncode/object-diff";

const updated = applyPatch(structuredClone(before), operations);

Always clone the target if you need to preserve the original.

Revert changes

import { revertPatch } from "@jayoncode/object-diff";

const undoOps = revertPatch(operations);
const restored = applyPatch(structuredClone(after), undoOps);

Common patterns

Scenario	Approach
Optimistic UI	Apply patch locally; revert on server error
Collaborative edit	Send patch ops over the wire, not full objects
Undo stack	Store patches; revertPatch for undo

Cheat sheet

patch(diffResult); // → operations
applyPatch(target, operations); // → patched object
revertPatch(operations); // → inverse ops

Next: Serialization — export diffs as JSON or Markdown.