Migrate types from dt~leaflet to this repo and its `package.json`

How to reproduce

• Leaflet version I’m using: 1.0.1

What behaviour I’m expecting and which behaviour I’m seeing

The package.json does not define types and the typescript definition is not included in this repo. See http://www.typescriptlang.org/docs/handbook/declaration-files/publishing.html for new practice for publishing.

[danzel]

Yes, lets close these 👍 Currently a typescript user will yarn add @types/leaflet, and I advise we keep it that way.

The types are hosted in the DefinitelyTyped repository, and can be contributed to there: https://github.com/DefinitelyTyped/DefinitelyTyped/tree/master/types/leaflet By having these externally we are not held up waiting for .d.ts updates for each release, and the types can be improved without requiring a new release.

[patrickarlt]

This kind of thing happened with PouchDB https://github.com/pouchdb/pouchdb/issues/5389 and it’s .d.ts files. In particular https://github.com/pouchdb/pouchdb/issues/5389#issuecomment-228610251, particularly:

it’s better for library authors not to ship their own index.d.ts files, unless they are well-versed in TypeScript and prepared to maintain it.

Seeing that none of the Leaflet core team has any Typescript experiance, I think @mourner’s suggestion of creating a seperate repo like leaflet-typings that can simply serve as a common point of discussion for those willing to maintain the types.