jsonmemory

Remember an object and tell me what actually changed.

One small problem. One obvious API. Very little setup. Immediate value.

JSON diffs are noisy. Most of the time the real question is simpler:

What meaningful values changed since the last time I saw this object?

import { memory } from "jsonmemory";

memory("checkout", data);       //  ✓ checkout stored

memory("checkout", updated);    //  prints exactly what changed:

checkout changed

user.plan
  "free" → "pro"

cart.items
  3 → 4

payment.status
  "pending" → "paid"

Install

npm i jsonmemory

One call, zero configuration, zero dependencies.

Usage

import { memory } from "jsonmemory";

const result = memory("user", user);
// =>
// {
//   changed: true,
//   first: false,
//   added:   [ { kind: "added", path: "full_name", to: "Eeza A" } ],
//   removed: [ { kind: "removed", path: "email", from: "[email protected]" } ],
//   modified:[ { kind: "modified", path: "user.plan", from: "free", to: "pro" } ],
//   entries: [...],
//   summary: "user changed\n ..."
// }

Ignore noisy fields

memory("user", user, {
  ignore: ["updated_at", "last_seen", "request_id"],
});

Storage modes

memory("user", data, { storage: "memory" });     // default — per-process
memory("user", data, { storage: ".jsonmemory" }); // persisted to .jsonmemory/memory.json

import { memory, configure, useStorage } from "jsonmemory";
configure({ adapter: myRedisAdapter });          // bring your own store
useStorage(".jsonmemory");                       // set a default directory

Deep diff without storage

import { diff } from "jsonmemory";

diff(oldObject, newObject);
// => [{ kind: "modified", path: "user.plan", from: "free", to: "pro" }, ...]

What you get

• deep comparison with dot-paths (user.plan, cart.items[2].name)
• array length changes as friendly counts (cart.items: 3 → 4)
• added / removed / modified groups plus one flat entries list
• ignore rules by leaf name or dotted path
• Dates, NaN, Map, Set, bigint all compare correctly (no false changes)
• file storage to survive process restarts
• zero runtime dependencies, ESM + CJS + .d.ts

License

MIT