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The JavaScript packages

The javascript API has been through several iterations and is currently split over a few libraries. This page describes how all these pieces fit together.

If you just want to know how to use Automerge in greenfield applications, here's how the library is intended to be used:

Install both the @automerge/automerge and @automerge/automerge-repo packages. Then install the networking and storage plugins you need (typically @automerge/automerge-repo-network-* and @automerge/automerge-repo-storage-*) packages. Take a look at the cookbook for examples of different ways of using these.

When you're making changes to an automerge document you should use the next API

The next API​

Over time we have made a number of changes to the automerge API which are not backwards compatible. In order to not break compatibility we have exposed the new API under a sub module of the library, this submodule used to be called "unstable" to reflect that we were not sure about it - but we're now fairly sure we like it so we're calling it "next" in expectation that it's what the next major version of automerge will look like.

Differences from stable​

  • In the old API javascript strings are represented as scalar strings (see the data model for details) whilst in "next" javascript strings are Text sequences (i.e. they support concurrent insertions and deletions). This means that you should use next.splice to modify strings in the next API. Scalar strings in the next API are represented as instances of the RawString class.
  • The next API exposes the diff and changeAt methods

Using the next API​

There are two ways to use the next API

Subpath Exports​

If you are either using JavaScript in a modern browser or on node > 16 then you can do the following:

import * as A from "@automerge/automerge/next";

Note that for this to work in typescript you will need to have the following in your tsconfig.json

    ...
    "module": "NodeNext",
    "moduleResolution": "Node16",
    ...

The { next } module​

If for whatever reason you can't use @automerge/automerge/next then you can do this:

import { next as A } from "@automerge/automerge";

How we got here​

Automerge Classic​

The first version of automerge was implemented in pure javascript and is what we now call automerge Classic. You can find it on NPM and GitHub. This project went through several iterations which changed quite dramatically.

@automerge/automerge-wasm and @automerge/automerge​

More recently we rewrote automerge in Rust and deployed it to javascript by compiling to a wasm package at @automerge/automerge-wasm. This wasm package is something we currently consider to be an implementation detail and should not be depended on by third parties. The @automerge/automerge package offers a very similar API to the original automerge package but implemented by forwarding logic to @automerge/automerge-wasm. It is consequently much faster.

@automerge/automerge-repo​

The core automerge libraries (both the original classic library and the WASM implementation) offer a compact storage format and a network agnostic sync protocol, but they don't actually do the work of wiring these things up to real storage engines (such as filesystems) or transports (such as websockets). automerge-repo implements all of this plumbing and is how we recommend using automerge going forward.