What's New in v3

v3 is a TypeScript rewrite. The behavior of the API is unchanged from v2 — the breaking changes are about packaging (ESM) and a set of renames that started as v2 deprecations.

Breaking Changes

ESM only. Notation is now an ES module. Import it with import { Notation } from 'notation' — CommonJS require() is no longer supported. (Why ESM?)
Node ≥ 20 required.
exports map. Only the package root (notation) and package.json are importable — no deep imports into lib/.
Nested classes removed. Notation.Error and Notation.Glob are gone; the classes are top-level named exports now.

Renames

Every removed member has a direct replacement with identical behavior:

Removed (v2)	Use instead (v3)
`Notation.Error`	`NotationError`
`Notation.Glob`	`NotationGlob`
`NotationGlob#levels`	`NotationGlob#notes`
`Notation#eachLevel()`	`Notation#eachNote()`
`Notation#aggregate()`	`Notation#expand()`
`Notation#delete()`	`Notation#remove()`
`Notation#renote()`	`Notation#rename()`
`Notation#copyToNew()`	`Notation#extract()`
`Notation#moveToNew()`	`Notation#extrude()`
`Notation.countLevels()`	`Notation.countNotes()`

Upgrading

// v2
const { Notation } = require('notation');
const glob = new Notation.Glob('x.*');
Notation.create(obj).aggregate();

// v3
import { Notation, NotationGlob } from 'notation';
const glob = new NotationGlob('x.*');
Notation.create(obj).expand();

Switch your imports to ESM, swap the renamed members per the table, and your v2 code runs unchanged. The full history is in the Changelog.