chore: consolidate the 2.0.0 changelog

.changeset/flattify-v2.md

@@ -2,6 +2,48 @@
 'flattify': major
 ---
 
-flattify 2.0 is a full rewrite in TypeScript: ESM and CommonJS builds, zero dependencies, published on npm and JSR (`@nandomb/flattify`), and tested on Node.js, Bun, Deno, browsers and Cloudflare Workers.
+**Why a major version?**
 
-**Breaking:** the default export `flattify(json, isFlattifyArray)` was removed. The migration guide ships with the new `flatten`/`unflatten` API.
+Flattify 2.0 is a full rewrite in TypeScript. The single default export `flattify(json, isFlattifyArray)` is replaced by named exports, `flatten` and `unflatten`, with different defaults. Code written for 1.x has to be updated (see Migration below).
+
+**Breaking changes**
+
+- **Named exports.** `flattify(...)` is replaced by `flatten(...)`: `import { flatten } from 'flattify'` or `const { flatten } = require('flattify')`.
+- **Arrays are flattened by default.** `flatten({ tags: ['a'] })` gives `{ 'tags.0': 'a' }`. The 1.x default, which turned arrays into JSON strings, is gone: pass `{ safe: true }` to keep arrays as arrays.
+- **Top-level arrays are flattened as a whole.** `flatten([{ id: 1 }])` gives `{ '0.id': 1 }` instead of flattening each item: use `array.map((item) => flatten(item))` for the 1.x behavior.
+- **JSON strings are no longer parsed.** Pass `JSON.parse(json)` instead of the string; anything but a plain object or an array throws a `TypeError`.
+- **Keys that contain the delimiter are escaped** (`{ 'a.b': 1 }` gives `{ 'a\.b': 1 }`), so they come back whole. Pass `{ escape: false }` to leave them as they are.
+- **TypeScript 5.0+** for the types.
+
+**Migration**
+
+```diff
+- const flattify = require('flattify');
+- flattify(data, true);
++ const { flatten } = require('flattify');
++ flatten(data);
+```
+
+| 1.x | 2.x |
+| --- | --- |
+| `flattify(obj, true)` | `flatten(obj)` |
+| `flattify(obj)` | `flatten(obj, { safe: true })` |
+| `flattify(array)` | `array.map((item) => flatten(item))` |
+| `flattify(jsonString)` | `flatten(JSON.parse(jsonString))` |
+
+**Fixed**
+
+- Nested arrays kept their path: `{ a: { tags: [1] }, b: { tags: [2] } }` gave `{ tags: '[2]' }` in 1.x, losing `a.tags`. It now gives `{ 'a.tags.0': 1, 'b.tags.0': 2 }`.
+- Calls no longer share state: 1.x stored the array option in a module-level variable.
+- Inherited properties are no longer read, and circular references no longer overflow the stack.
+
+**New**
+
+- **`unflatten`**, the reverse of `flatten`: `unflatten(flatten(data))` gives back `data`, including dates, class instances, `null`, empty objects and arrays, and keys with dots in them. `asArray` gives back an array given to `flatten`.
+- **Type inference:** every path and value of the result is typed (`Flatten<T>`, `Unflatten<T>`), for every option that changes them.
+- **Options:** `delimiter`, `maxDepth`, `safe`, `keepEmpty`, `escape`, `circular`, `transformKey` and `preserve` for `flatten`; `delimiter`, `object`, `overwrite`, `arrayLimit`, `asArray`, `escape` and `transformKey` for `unflatten`.
+- **Three notations:** `items.0.id` (dot), `items[0].id` (bracket, and `unflatten` reads form fields such as `items[0][id]`) and `/items/0/id` (JSON Pointer, RFC 6901).
+- **`flattify/path`:** `get`, `set`, `has`, `del`, `paths`, `parsePath`, `stringifyPath` and `escapeKey`, with autocompleted paths and type-checked values.
+- **Safe on untrusted input:** no prototype pollution through `__proto__`, `constructor` or `prototype`, no stack overflow on deep or circular input, and `arrayLimit` against huge sparse arrays. Covered by tests, including fuzzing.
+- **Everywhere:** ESM and CommonJS builds with zero dependencies, published on npm and on JSR as [`@nandomb/flattify`](https://jsr.io/@nandomb/flattify), and tested on Node.js 22, 24 and 26, Bun, Deno, Chromium, Firefox, WebKit and Cloudflare Workers.
+- **Trusted releases:** published from CI without long-lived tokens, with npm provenance, and only live after a maintainer approves them with 2FA (staged publishing).

README.md

@@ -1,4 +1,4 @@
-# [flattify](https://github.com/NandoMB/flattify)
+# [Flattify](https://github.com/NandoMB/flattify)
 
 [![npm version](https://img.shields.io/npm/v/flattify.svg)](https://www.npmjs.com/package/flattify)
 [![JSR](https://jsr.io/badges/@nandomb/flattify)](https://jsr.io/@nandomb/flattify)
@@ -17,14 +17,14 @@ Turn nested objects into flat `path → value` pairs **and back, without losing
 - **Checked, not claimed:** 100% test coverage, thousands of random round trips per run, and every [comparison](#why-flattify) with other libraries verified in CI
 - Zero dependencies, ESM and CommonJS, on [npm](https://www.npmjs.com/package/flattify) and [JSR](https://jsr.io/@nandomb/flattify). Runs on Node.js, Bun, Deno, browsers and Cloudflare Workers
 
-> Upgrading from flattify 1.x? See [Migrating](#migrating).
+> Upgrading from Flattify 1.x? See [Migrating](#migrating).
 
 ## Contents
 
 - [Installation](#installation)
 - [Quick start](#quick-start)
 - [Data integrity](#data-integrity)
-- [Why flattify?](#why-flattify)
+- [Why Flattify?](#why-flattify)
 - [Use cases](#use-cases)
 - [API](#api): [`flatten`](#flatteninput-options), [`unflatten`](#unflatteninput-options), [notations](#notations), [`flattify/path`](#flattifypath)
 - [Types](#types)
@@ -88,7 +88,7 @@ back.items[0].sku;        // string
 
 ## Data integrity
 
-Most libraries lose something on the way: a `Date` becomes `{}`, `null` disappears, an empty list vanishes, `'utm.source'` is split in two. flattify keeps all of it:
+Most libraries lose something on the way: a `Date` becomes `{}`, `null` disappears, an empty list vanishes, `'utm.source'` is split in two. Flattify keeps all of it:
 
 ```ts
 const input = {
@@ -123,11 +123,11 @@ back['utm.source'];                  // 'newsletter', still one key
 
 Each guarantee is covered by the test suite, and the round trip is checked on thousands of random objects on every run ([fast-check](https://fast-check.dev)), for every notation.
 
-## Why flattify?
+## Why Flattify?
 
 Every row is checked by [`bench/claims.spec.ts`](./bench/claims.spec.ts) against flat 6.0.1, flattie 1.1.1, nestie 1.0.3, es-toolkit 1.52.0 and radashi 12.9.6, on every change in CI (`pnpm claims`).
 
-| | flattify | [flat](https://www.npmjs.com/package/flat) | [flattie](https://www.npmjs.com/package/flattie) / [nestie](https://www.npmjs.com/package/nestie) | [es-toolkit](https://www.npmjs.com/package/es-toolkit) | [radashi](https://www.npmjs.com/package/radashi) |
+| | Flattify | [flat](https://www.npmjs.com/package/flat) | [flattie](https://www.npmjs.com/package/flattie) / [nestie](https://www.npmjs.com/package/nestie) | [es-toolkit](https://www.npmjs.com/package/es-toolkit) | [radashi](https://www.npmjs.com/package/radashi) |
 | --- | --- | --- | --- | --- | --- |
 | Keys with the delimiter survive the round trip | ✅ | ❌ | ❌ | – | ❌ |
 | Keeps `Date` and `Map` as values | ✅ | ✅ | ❌ dropped | ✅ | ✅ |
@@ -144,7 +144,7 @@ Every row is checked by [`bench/claims.spec.ts`](./bench/claims.spec.ts) against
 | ESM and CommonJS | ✅ | ❌ v6 is ESM only | ✅ | ✅ | ✅ |
 | Size (min + gzip) | 2.3 kB | 0.7 kB | 0.35 kB | 0.34 kB | 0.8 kB |
 
-flattify is bigger because it does more: the checks above, three notations, escaping and clear error messages. `flattify/path` is a separate import, so it only counts when you use it.
+Flattify is bigger because it does more: the checks above, three notations, escaping and clear error messages. `flattify/path` is a separate import, so it only counts when you use it.
 
 ## Use cases
 
@@ -308,7 +308,7 @@ CI runs the tests on Node.js 22, 24 and 26, Bun, Deno, Chromium, Firefox, WebKit
 
 Same option names (`delimiter`, `maxDepth`, `safe`, `object`, `overwrite`, `transformKey`), with safer defaults:
 
-| | `flat` | flattify |
+| | `flat` | Flattify |
 | --- | --- | --- |
 | Result type | you pass it: `flatten<T, R>()` | inferred |
 | Keys with the delimiter | split in two on the way back | escaped; `{ escape: false }` for the old behavior |
@@ -318,7 +318,7 @@ Same option names (`delimiter`, `maxDepth`, `safe`, `object`, `overwrite`, `tran
 | Class instances | flattened | kept as values |
 | Circular references | stack overflow | `TypeError`, or `circular: 'skip'` |
 
-### From flattify 1.x
+### From Flattify 1.x
 
 2.0 is a rewrite with named exports: