proj9-js

Experimental JavaScript/TypeScript port inspired by PROJ 9 semantics.

Status

• v0.1.0: supports only EPSG:4326 ↔ EPSG:3857 transforms using a pipeline/step architecture.
• Bundles data/proj.db and exposes stable APIs to locate it (DB not used yet).

Install

npm i proj9-js

Usage

import { transform, createTransformer, getBundledProjDbPath } from "proj9-js";

const xy = transform("EPSG:4326", "EPSG:3857", [180, 0]);
const ll = transform("EPSG:3857", "EPSG:4326", xy);

const t = createTransformer("EPSG:4326", "EPSG:3857");
const xy2 = t.forward([12, 34]);

console.log(getBundledProjDbPath());

Notes on proj.db

This package ships a data/proj.db asset and provides:

• getBundledProjDbPath(): string
• getBundledProjDbBuffer(): Buffer
• setProjDataDir(path: string): void

The DB is not read yet (planned for v0.2.0). You can refresh data/proj.db later via npm run download:projdb once you pick a specific PROJ release source.