Upgrading from 0.x to 1.0

Version 1.0 migrates the entire library to native ES Modules (ESM). If your application was using require('event-storage') you will need to update your import statements and a few API references.

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1. Node.js version

ESM support requires Node.js 18 or later. Check your version:

node --version

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2. Update your package.json

Your own project must opt in to ESM. Add "type": "module" to your package.json:

{
  "type": "module"
}

If you cannot migrate your whole project to ESM, you can rename individual files from .js to .mjs — Node.js treats .mjs files as ESM regardless of the "type" field.

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3. Replace require() with import

Basic import

// Before (0.x)
const EventStore = require('event-storage');

// After (1.0)
import { EventStore } from 'event-storage';

Named exports that were previously properties

In 0.x, constants and sub-classes were attached as properties on the default export. Constants are now individual named exports, while sub-classes remain accessible as properties of the parent class:

0.x	1.0
EventStore.ExpectedVersion	import { ExpectedVersion } from 'event-storage'
EventStore.OptimisticConcurrencyError	import { OptimisticConcurrencyError } from 'event-storage'
EventStore.LOCK_THROW	import { LOCK_THROW } from 'event-storage'
EventStore.LOCK_RECLAIM	import { LOCK_RECLAIM } from 'event-storage'
require('event-storage').Storage	import { Storage } from 'event-storage'
Storage.ReadOnly	Storage.ReadOnly (unchanged — still a property of Storage)
Storage.StorageLockedError	import { StorageLockedError } from 'event-storage'
Index.ReadOnly	Index.ReadOnly (unchanged — still a property of Index)
Index.Entry	Index.Entry (unchanged — still a property of Index)

Full import surface

All public exports from the package entry point:

import {
  EventStore, ExpectedVersion, OptimisticConcurrencyError,
  EventStream,
  Storage, StorageLockedError,
  Index,
  Consumer,
  LOCK_THROW, LOCK_RECLAIM
} from 'event-storage';

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4. Common patterns updated

Creating an event store

// Before
const EventStore = require('event-storage');
const eventstore = new EventStore('my-store', { storageDirectory: './data' });

// After
import { EventStore } from 'event-storage';
const eventstore = new EventStore('my-store', { storageDirectory: './data' });

Optimistic concurrency

// Before
eventstore.commit('my-stream', events, EventStore.ExpectedVersion.EmptyStream, callback);
// …and catching errors:
if (err instanceof EventStore.OptimisticConcurrencyError) { … }

// After
import { EventStore, ExpectedVersion, OptimisticConcurrencyError } from 'event-storage';
eventstore.commit('my-stream', events, ExpectedVersion.EmptyStream, callback);
if (err instanceof OptimisticConcurrencyError) { … }

Lock modes

// Before
const EventStore = require('event-storage');
const eventstore = new EventStore('my-store', {
    storageConfig: { lock: EventStore.LOCK_RECLAIM }
});

// After
import { EventStore, LOCK_RECLAIM } from 'event-storage';
const eventstore = new EventStore('my-store', {
    storageConfig: { lock: LOCK_RECLAIM }
});

Using the Storage class directly

// Before
const Storage = require('event-storage').Storage;
const ReadOnlyStorage = Storage.ReadOnly;
const store = new ReadOnlyStorage('mystore', { dataDirectory: './data' });

// After
import { Storage } from 'event-storage';
const store = new Storage.ReadOnly('mystore', { dataDirectory: './data' });

Custom serialization / compression

// Before
const { encode, decode } = require('@msgpack/msgpack');

// After
import { encode, decode } from '@msgpack/msgpack';

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5. Relative file imports require .js extensions

If your project imports internal modules from node_modules/event-storage by path (uncommon), note that ESM requires explicit file extensions. This change is internal to the library and should not affect application code that imports from 'event-storage'.

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6. __dirname / __filename

These globals are not available in ESM. If you reference them in your own application code, replace them with:

import { fileURLToPath } from 'url';
import path from 'path';

const __filename = fileURLToPath(import.meta.url);
const __dirname  = path.dirname(__filename);

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7. Dynamic require() / createRequire

If you have tooling or test helpers that still need CJS-style loading, use createRequire:

import { createRequire } from 'module';
const require = createRequire(import.meta.url);

This is a compatibility shim and is generally not needed when consuming event-storage itself.