docs/custom.md - pouchdb - Git at Google

 ---
 layout: 2ColLeft
 title: Custom Builds
 sidebar: nav.html
 ---

 PouchDB supports custom builds, meaning you can pick and choose the features of
 PouchDB that you want to use, potentially resulting in smaller bundle sizes
 and faster build times.

 PouchDB exposes its custom builds via separate packages available on npm. All of
 these packages follow the format `pouchdb-<name>` and can be installed using `npm install`.

 Some packages are included by default in the main `pouchdb` package, whereas
 others (including third-party packages) must be installed separately.

 {% include alert/start.html variant="warning"%}
 {% markdown %}

 Custom builds require an [npm][]-based build system, using a bundler
 like [Browserify][], [Webpack][], [SystemJS][], [Rollup][], or [JSPM][]. Tools like
 [Bower][], as well as direct download of prebuilt JavaScript files, are not supported.

 [Browserify]: http://browserify.org/
 [Webpack]: http://webpack.github.io/
 [SystemJS]: https://github.com/systemjs/systemjs
 [JSPM]: http://jspm.io/
 [Rollup]: http://rollupjs.org/
 [npm]: http://npmjs.com/
 [Bower]: http://bower.io

 {% endmarkdown %}
 {% include alert/end.html%}

 PouchDB packages come in three flavors: *presets*, *plugins*, and
 *utilities*.

 **Presets** are a collection of plugins, which expose a `PouchDB` object that is ready to be used.

 **Plugins** are features that can be added to a `PouchDB` instance using the `PouchDB.plugin()`
 API.

 **Utilities** are grab-bags of helper functions, and are only recommended for advanced use cases.

 #### Quick links

 * [Presets](#presets)
 * [Plugins](#plugins)
 * [Utilities](#utilities)

 {% include anchor.html class="h2" title="Presets" hash="presets" %}

 Presets export a `PouchDB` object and contain a built-in set of PouchDB
 plugins. You are free to create your own presets, but PouchDB provides a few first-party presets to address common use cases.

 ### pouchdb-browser

 The `pouchdb-browser` preset contains the version of PouchDB that is designed
 for the browser. In particular, it ships with the IndexedDB and WebSQL adapters
 as its default adapters. It also contains the replication, HTTP, and map/reduce plugins.

 Use this preset if you only want to use PouchDB in the browser,
 and don't want to use it in Node.js. (E.g. to avoid installing LevelDB.)

 #### Example Usage

 ```bash
 npm install pouchdb-browser
 ```

 ```js
 var PouchDB = require('pouchdb-browser');
 var db = new PouchDB('mydb');
 ```

 #### Source code (simplified)

 ```js
 var PouchDB = require('pouchdb-core')
   .plugin(require('pouchdb-adapter-idb'))
   .plugin(require('pouchdb-adapter-websql'))
   .plugin(require('pouchdb-adapter-http'))
   .plugin(require('pouchdb-mapreduce'))
   .plugin(require('pouchdb-replication'));
 ```

 ### pouchdb-node

 The `pouchdb-node` preset contains the version of PouchDB that is designed for
 Node.js. In particular, it uses the LevelDB adapter and doesn't ship with the
 IndexedDB or WebSQL adapters. It also contains the replication, HTTP, and map/reduce plugins.

 Use this preset if you are only using PouchDB in Node, and not in the browser.

 #### Example Usage

 ```bash
 npm install pouchdb-node
 ```

 ```js
 var PouchDB = require('pouchdb-node');
 var db = new PouchDB('mydb');
 ```

 #### Source code (simplified)

 ```js
 var PouchDB = require('pouchdb-core')
   .plugin(require('pouchdb-adapter-leveldb'))
   .plugin(require('pouchdb-adapter-http'))
   .plugin(require('pouchdb-mapreduce'))
   .plugin(require('pouchdb-replication'));
 ```

 ### pouchdb-core

 The `pouchdb-core` package is a special preset in that it exposes the minimum
 number of APIs. It contains zero plugins and is designed to be used in addition
 with other plugins. By itself, it probably isn't very useful.

 #### Example Usage

 ```bash
 npm install pouchdb-core
 ```

 ```js
 var PouchDB = require('pouchdb-core');
 PouchDB.plugin(/* attach plugins to make me more interesting! */);
 ```

 {% include anchor.html class="h2" title="Plugins" hash="plugins" %}

 Plugins contain functionality that can be added to a `PouchDB` instance using `PouchDB.plugin()`. There are many [third-party plugins](/external.html), but the ones described below are first-party plugins, which are given the same level of support as PouchDB itself. Some first-party plugins are included in the default `pouchdb` build, whereas others aren't.

 There is also a special type of plugin called an _adapter plugin_.  Adapter plugins (such as IndexedDB, WebSQL, LevelDB, and HTTP) determine the storage format that
 PouchDB uses. For the non-HTTP adapters, the plugin order matters, i.e. if you
 want IndexedDB to be preferred to WebSQL, then you should load it first. (Notice that `pouchdb-browser` does exactly this.)

 ### pouchdb-adapter-idb

 The primary adapter used by PouchDB in the browser, using IndexedDB. The adapter
 name is `'idb'`.

 #### Example usage

 ```bash
 npm install pouchdb-adapter-idb
 ```

 ```js
 PouchDB.plugin(require('pouchdb-adapter-idb'));
 var db = new PouchDB('mydb', {adapter: 'idb'});
 console.log(db.adapter); // 'idb'
 ```

 ### pouchdb-adapter-websql

 The secondary adapter used by PouchDB in the browser, using WebSQL. The adapter
 name is `'websql'`.

 #### Example usage

 ```bash
 npm install pouchdb-adapter-websql
 ```

 ```js
 PouchDB.plugin(require('pouchdb-adapter-websql'));
 var db = new PouchDB('mydb', {adapter: 'websql'});
 console.log(db.adapter); // 'websql'
 ```

 ### pouchdb-adapter-leveldb

 The primary adapter used by PouchDB in Node.js, using LevelDB. The adapter name
 is `'leveldb'`.

 #### Example usage

 ```bash
 npm install pouchdb-adapter-leveldb
 ```

 ```js
 PouchDB.plugin(require('pouchdb-adapter-leveldb'));
 var db = new PouchDB('mydb', {adapter: 'leveldb'});
 console.log(db.adapter); // 'leveldb'
 ```

 ### pouchdb-adapter-http

 The primary adapter used by PouchDB in both Node.js and the browser for communicating
 with external CouchDB (or CouchDB-like) servers.

 This plugin can be added to PouchDB in any order, and is somewhat special in that
 you must pass in a name like `'http://...'` in order to use it. The adapter name
 is either `'http'` or `'https'` depending on the protocol.

 #### Example usage

 ```bash
 npm install pouchdb-adapter-http
 ```

 ```js
 PouchDB.plugin(require('pouchdb-adapter-http'));
 var db = new PouchDB('http://127.0.0.1:5984/mydb');
 console.log(db.adapter); // 'http'
 ```

 ### pouchdb-adapter-memory

 An optional adapter that works in the browser and Node.js, fully in-memory. The adapter name
 is `'memory'`.

 #### Example usage

 ```bash
 npm install pouchdb-adapter-memory
 ```

 ```js
 PouchDB.plugin(require('pouchdb-adapter-memory'));
 var db = new PouchDB('mydb', {adapter: 'memory'});
 console.log(db.adapter); // 'memory'
 ```

 ### pouchdb-adapter-localstorage

 An optional adapter that works in the browser using LocalStorage. The adapter name
 is `'localstorage'`.

 #### Example usage

 ```bash
 npm install pouchdb-adapter-localstorage
 ```

 ```js
 PouchDB.plugin(require('pouchdb-adapter-localstorage'));
 var db = new PouchDB('mydb', {adapter: 'localstorage'});
 console.log(db.adapter); // 'localstorage'
 ```

 ### pouchdb-adapter-fruitdown

 An optional adapter that works in the browser using IndexedDB via [fruitdown](https://github.com/nolanlawson/fruitdown). The adapter name
 is `'fruitdown'`.

 #### Example usage

 ```bash
 npm install pouchdb-adapter-fruitdown
 ```

 ```js
 PouchDB.plugin(require('pouchdb-adapter-fruitdown'));
 var db = new PouchDB('mydb', {adapter: 'fruitdown'});
 console.log(db.adapter); // 'fruitdown'
 ```

 ### pouchdb-adapter-node-websql

 An optional adapter that works in Node.js using SQLite via [node-websql](https://github.com/nolanlawson/node-websql). The adapter name
 is `'websql'`.

 #### Example usage

 ```bash
 npm install pouchdb-adapter-node-websql
 ```

 ```js
 PouchDB.plugin(require('pouchdb-adapter-node-websql'));
 var db = new PouchDB('mydb', {adapter: 'websql'});
 console.log(db.adapter); // 'websql'
 ```

 ### pouchdb-adapter-indexeddb

 {% include alert/start.html variant="warning"%}
 {% markdown %}

 **Warning: experimental.** You probably don't want to use this yet. &#x1F609;

 {% endmarkdown %}
 {% include alert/end.html%}

 An experimental next-generation IndexedDB adapter, also known as "idb-next". Currently not shipped as part of PouchDB. The adapter name is `'indexeddb'`.

 #### Example usage

 ```bash
 npm install pouchdb-adapter-indexeddb
 ```

 ```js
 PouchDB.plugin(require('pouchdb-adapter-indexeddb'));
 var db = new PouchDB('mydb', {adapter: 'indexeddb'});
 console.log(db.adapter); // 'indexeddb'
 ```

 ### pouchdb-find

 PouchDB's "Mango" query API, exposed via the `find()`, `listIndexes(), `createIndex()`, and `deleteIndex()` methods. Not shipped by default in PouchDB.

 #### Example usage

 ```bash
 npm install pouchdb-find
 ```

 ```js
 PouchDB.plugin(require('pouchdb-find'));
 var db = new PouchDB('mydb');
 db.find(/* see API docs for full info */);
 ```

 ### pouchdb-mapreduce

 PouchDB's map/reduce API, exposed via the `query()` and `viewCleanup()` methods. Ships by default in PouchDB.

 #### Example usage

 ```bash
 npm install pouchdb-mapreduce
 ```

 ```js
 PouchDB.plugin(require('pouchdb-mapreduce'));
 var db = new PouchDB('mydb');
 db.query(/* see query API docs for full info */);
 ```

 ### pouchdb-replication

 PouchDB's replication API, exposed via the `replicate()` and `sync()` methods. Ships by default in PouchDB.

 #### Example usage

 ```bash
 npm install pouchdb-replication
 ```

 ```js
 PouchDB.plugin(require('pouchdb-replication'));
 var db = new PouchDB('mydb');
 db.replicate(/* see replicate/sync API docs for full info */);
 ```

 {% include anchor.html class="h2" title="Utilities" hash="utilities" %}

 These utilities are intended only for advanced users of PouchDB, such as
 third-party plugin authors. Formerly, many of them were exposed via the `extras/` API, which
 is now deprecated.

 Most of these are internal, and the APIs are not thoroughly documented. You will
 most likely need to read the source code to understand how they work.

 {% include alert/start.html variant="warning"%}
 {% markdown %}

 **Warning:** you are entering a semver-free zone.

 In contrast to the presets and plugins listed above, **none of the following packages
 follow semver**. Their versions are pinned to PouchDB's, and may change at any time
 without warning. You are strongly recommended to **use exact versions** when installing these packages.

 {% endmarkdown %}
 {% include alert/end.html%}

 ### pouchdb-abstract-mapreduce

 The underlying logic for secondary indexes, as expressed in both `pouchdb-mapreduce` and `pouchdb-find`. Both packages use this package under the hood.

 #### Example usage

 ```bash
 npm install --save-exact pouchdb-abstract-mapreduce
 ```

 ### pouchdb-adapter-utils

 Utilities for PouchDB adapters.

 #### Example usage

 ```bash
 npm install --save-exact pouchdb-adapter-utils
 ```

 ### pouchdb-ajax

 PouchDB's `ajax()` function.

 #### Example usage

 ```bash
 npm install --save-exact pouchdb-ajax
 ```

 ### pouchdb-binary-utils

 Utilities for operating on binary strings and Buffers/Blobs.

 #### Example usage

 ```bash
 npm install --save-exact pouchdb-binary-utils
 ```

 ### pouchdb-checkpointer

 Tool to write a checkpoint, e.g. during replication.

 #### Example usage

 ```bash
 npm install --save-exact pouchdb-checkpointer
 ```

 ### pouchdb-collate

 Collation functions for PouchDB map/reduce.

 #### Example usage

 ```bash
 npm install --save-exact pouchdb-collate
 ```

 ### pouchdb-collections

 ES6 shims for Map and Set as used in PouchDB.

 #### Example usage

 ```bash
 npm install --save-exact pouchdb-collections
 ```

 ### pouchdb-debug

 The `PouchDB.debug()` API, expressed as a separate plugin. May eventually be removed from PouchDB core.

 #### Example usage

 ```bash
 npm install --save-exact pouchdb-debug
 ```

 ### pouchdb-errors

 Errors exposed by PouchDB.

 #### Example usage

 ```bash
 npm install --save-exact pouchdb-errors
 ```

 ### pouchdb-generate-replication-id

 Function to generate a replication ID to mark progress during replications.

 #### Example usage

 ```bash
 npm install --save-exact pouchdb-generate-replication-id
 ```

 ### pouchdb-json

 Utilities for safely stringifying and parsing JSON.

 #### Example usage

 ```bash
 npm install --save-exact pouchdb-json
 ```

 ### pouchdb-mapreduce-utils

 Utilities used by `pouchdb-mapreduce`.

 #### Example usage

 ```bash
 npm install --save-exact pouchdb-mapreduce-utils
 ```

 ### pouchdb-md5

 Utilities for calculating MD5 checksums.

 #### Example usage

 ```bash
 npm install --save-exact pouchdb-md5
 ```

 ### pouchdb-merge

 PouchDB's CouchDB-style document merge algorithm.

 #### Example usage

 ```bash
 npm install --save-exact pouchdb-merge
 ```

 ### pouchdb-promise

 A `Promise` object, polyfilled using `lie` if Promises aren't available globally.

 #### Example usage

 ```bash
 npm install --save-exact pouchdb-promise
 ```

 ### pouchdb-selector-core

 The core Mango selector logic, which allows the selector to be used both by `pouchdb-find` and for filtering/replication.

 #### Example usage

 ```bash
 npm install --save-exact pouchdb-selector-core
 ```

 ### pouchdb-utils

 A potpourri of miscellaneous utilities used by PouchDB and its sub-packages.

 #### Example usage

 ```bash
 npm install --save-exact pouchdb-utils
 ```

 ### sublevel-pouchdb

 Fork of [level-sublevel](https://github.com/dominictarr/level-sublevel)
 with ony the subset of the API that PouchDB uses.

 #### Example usage

 ```bash
 npm install --save-exact sublevel-pouchdb
 ```
	---
	layout: 2ColLeft
	title: Custom Builds
	sidebar: nav.html
	---

	PouchDB supports custom builds, meaning you can pick and choose the features of
	PouchDB that you want to use, potentially resulting in smaller bundle sizes
	and faster build times.

	PouchDB exposes its custom builds via separate packages available on npm. All of
	these packages follow the format `pouchdb-<name>` and can be installed using `npm install`.

	Some packages are included by default in the main `pouchdb` package, whereas
	others (including third-party packages) must be installed separately.

	{% include alert/start.html variant="warning"%}
	{% markdown %}

	Custom builds require an [npm][]-based build system, using a bundler
	like [Browserify][], [Webpack][], [SystemJS][], [Rollup][], or [JSPM][]. Tools like
	[Bower][], as well as direct download of prebuilt JavaScript files, are not supported.

	[Browserify]: http://browserify.org/
	[Webpack]: http://webpack.github.io/
	[SystemJS]: https://github.com/systemjs/systemjs
	[JSPM]: http://jspm.io/
	[Rollup]: http://rollupjs.org/
	[npm]: http://npmjs.com/
	[Bower]: http://bower.io

	{% endmarkdown %}
	{% include alert/end.html%}

	PouchDB packages come in three flavors: presets, plugins, and
	utilities.

	Presets are a collection of plugins, which expose a `PouchDB` object that is ready to be used.

	Plugins are features that can be added to a `PouchDB` instance using the `PouchDB.plugin()`
	API.

	Utilities are grab-bags of helper functions, and are only recommended for advanced use cases.

	#### Quick links

	* [Presets](#presets)
	* [Plugins](#plugins)
	* [Utilities](#utilities)

	{% include anchor.html class="h2" title="Presets" hash="presets" %}

	Presets export a `PouchDB` object and contain a built-in set of PouchDB
	plugins. You are free to create your own presets, but PouchDB provides a few first-party presets to address common use cases.

	### pouchdb-browser

	The `pouchdb-browser` preset contains the version of PouchDB that is designed
	for the browser. In particular, it ships with the IndexedDB and WebSQL adapters
	as its default adapters. It also contains the replication, HTTP, and map/reduce plugins.

	Use this preset if you only want to use PouchDB in the browser,
	and don't want to use it in Node.js. (E.g. to avoid installing LevelDB.)

	#### Example Usage

	```bash
	npm install pouchdb-browser
	```

	```js
	var PouchDB = require('pouchdb-browser');
	var db = new PouchDB('mydb');
	```

	#### Source code (simplified)

	```js
	var PouchDB = require('pouchdb-core')
	.plugin(require('pouchdb-adapter-idb'))
	.plugin(require('pouchdb-adapter-websql'))
	.plugin(require('pouchdb-adapter-http'))
	.plugin(require('pouchdb-mapreduce'))
	.plugin(require('pouchdb-replication'));
	```

	### pouchdb-node

	The `pouchdb-node` preset contains the version of PouchDB that is designed for
	Node.js. In particular, it uses the LevelDB adapter and doesn't ship with the
	IndexedDB or WebSQL adapters. It also contains the replication, HTTP, and map/reduce plugins.

	Use this preset if you are only using PouchDB in Node, and not in the browser.

	#### Example Usage

	```bash
	npm install pouchdb-node
	```

	```js
	var PouchDB = require('pouchdb-node');
	var db = new PouchDB('mydb');
	```

	#### Source code (simplified)

	```js
	var PouchDB = require('pouchdb-core')
	.plugin(require('pouchdb-adapter-leveldb'))
	.plugin(require('pouchdb-adapter-http'))
	.plugin(require('pouchdb-mapreduce'))
	.plugin(require('pouchdb-replication'));
	```

	### pouchdb-core

	The `pouchdb-core` package is a special preset in that it exposes the minimum
	number of APIs. It contains zero plugins and is designed to be used in addition
	with other plugins. By itself, it probably isn't very useful.

	#### Example Usage

	```bash
	npm install pouchdb-core
	```

	```js
	var PouchDB = require('pouchdb-core');
	PouchDB.plugin(/* attach plugins to make me more interesting! */);
	```

	{% include anchor.html class="h2" title="Plugins" hash="plugins" %}

	Plugins contain functionality that can be added to a `PouchDB` instance using `PouchDB.plugin()`. There are many [third-party plugins](/external.html), but the ones described below are first-party plugins, which are given the same level of support as PouchDB itself. Some first-party plugins are included in the default `pouchdb` build, whereas others aren't.

	There is also a special type of plugin called an _adapter plugin_. Adapter plugins (such as IndexedDB, WebSQL, LevelDB, and HTTP) determine the storage format that
	PouchDB uses. For the non-HTTP adapters, the plugin order matters, i.e. if you
	want IndexedDB to be preferred to WebSQL, then you should load it first. (Notice that `pouchdb-browser` does exactly this.)

	### pouchdb-adapter-idb

	The primary adapter used by PouchDB in the browser, using IndexedDB. The adapter
	name is `'idb'`.

	#### Example usage

	```bash
	npm install pouchdb-adapter-idb
	```

	```js
	PouchDB.plugin(require('pouchdb-adapter-idb'));
	var db = new PouchDB('mydb', {adapter: 'idb'});
	console.log(db.adapter); // 'idb'
	```

	### pouchdb-adapter-websql

	The secondary adapter used by PouchDB in the browser, using WebSQL. The adapter
	name is `'websql'`.

	#### Example usage

	```bash
	npm install pouchdb-adapter-websql
	```

	```js
	PouchDB.plugin(require('pouchdb-adapter-websql'));
	var db = new PouchDB('mydb', {adapter: 'websql'});
	console.log(db.adapter); // 'websql'
	```

	### pouchdb-adapter-leveldb

	The primary adapter used by PouchDB in Node.js, using LevelDB. The adapter name
	is `'leveldb'`.

	#### Example usage

	```bash
	npm install pouchdb-adapter-leveldb
	```

	```js
	PouchDB.plugin(require('pouchdb-adapter-leveldb'));
	var db = new PouchDB('mydb', {adapter: 'leveldb'});
	console.log(db.adapter); // 'leveldb'
	```

	### pouchdb-adapter-http

	The primary adapter used by PouchDB in both Node.js and the browser for communicating
	with external CouchDB (or CouchDB-like) servers.

	This plugin can be added to PouchDB in any order, and is somewhat special in that
	you must pass in a name like `'http://...'` in order to use it. The adapter name
	is either `'http'` or `'https'` depending on the protocol.

	#### Example usage

	```bash
	npm install pouchdb-adapter-http
	```

	```js
	PouchDB.plugin(require('pouchdb-adapter-http'));
	var db = new PouchDB('http://127.0.0.1:5984/mydb');
	console.log(db.adapter); // 'http'
	```

	### pouchdb-adapter-memory

	An optional adapter that works in the browser and Node.js, fully in-memory. The adapter name
	is `'memory'`.

	#### Example usage

	```bash
	npm install pouchdb-adapter-memory
	```

	```js
	PouchDB.plugin(require('pouchdb-adapter-memory'));
	var db = new PouchDB('mydb', {adapter: 'memory'});
	console.log(db.adapter); // 'memory'
	```

	### pouchdb-adapter-localstorage

	An optional adapter that works in the browser using LocalStorage. The adapter name
	is `'localstorage'`.

	#### Example usage

	```bash
	npm install pouchdb-adapter-localstorage
	```

	```js
	PouchDB.plugin(require('pouchdb-adapter-localstorage'));
	var db = new PouchDB('mydb', {adapter: 'localstorage'});
	console.log(db.adapter); // 'localstorage'
	```

	### pouchdb-adapter-fruitdown

	An optional adapter that works in the browser using IndexedDB via [fruitdown](https://github.com/nolanlawson/fruitdown). The adapter name
	is `'fruitdown'`.

	#### Example usage

	```bash
	npm install pouchdb-adapter-fruitdown
	```

	```js
	PouchDB.plugin(require('pouchdb-adapter-fruitdown'));
	var db = new PouchDB('mydb', {adapter: 'fruitdown'});
	console.log(db.adapter); // 'fruitdown'
	```

	### pouchdb-adapter-node-websql

	An optional adapter that works in Node.js using SQLite via [node-websql](https://github.com/nolanlawson/node-websql). The adapter name
	is `'websql'`.

	#### Example usage

	```bash
	npm install pouchdb-adapter-node-websql
	```

	```js
	PouchDB.plugin(require('pouchdb-adapter-node-websql'));
	var db = new PouchDB('mydb', {adapter: 'websql'});
	console.log(db.adapter); // 'websql'
	```

	### pouchdb-adapter-indexeddb

	{% include alert/start.html variant="warning"%}
	{% markdown %}

	Warning: experimental. You probably don't want to use this yet. 😉

	{% endmarkdown %}
	{% include alert/end.html%}

	An experimental next-generation IndexedDB adapter, also known as "idb-next". Currently not shipped as part of PouchDB. The adapter name is `'indexeddb'`.

	#### Example usage

	```bash
	npm install pouchdb-adapter-indexeddb
	```

	```js
	PouchDB.plugin(require('pouchdb-adapter-indexeddb'));
	var db = new PouchDB('mydb', {adapter: 'indexeddb'});
	console.log(db.adapter); // 'indexeddb'
	```

	### pouchdb-find

	PouchDB's "Mango" query API, exposed via the `find()`, `listIndexes(), `createIndex()`, and `deleteIndex()` methods. Not shipped by default in PouchDB.

	#### Example usage

	```bash
	npm install pouchdb-find
	```

	```js
	PouchDB.plugin(require('pouchdb-find'));
	var db = new PouchDB('mydb');
	db.find(/* see API docs for full info */);
	```

	### pouchdb-mapreduce

	PouchDB's map/reduce API, exposed via the `query()` and `viewCleanup()` methods. Ships by default in PouchDB.

	#### Example usage

	```bash
	npm install pouchdb-mapreduce
	```

	```js
	PouchDB.plugin(require('pouchdb-mapreduce'));
	var db = new PouchDB('mydb');
	db.query(/* see query API docs for full info */);
	```

	### pouchdb-replication

	PouchDB's replication API, exposed via the `replicate()` and `sync()` methods. Ships by default in PouchDB.

	#### Example usage

	```bash
	npm install pouchdb-replication
	```

	```js
	PouchDB.plugin(require('pouchdb-replication'));
	var db = new PouchDB('mydb');
	db.replicate(/* see replicate/sync API docs for full info */);
	```

	{% include anchor.html class="h2" title="Utilities" hash="utilities" %}

	These utilities are intended only for advanced users of PouchDB, such as
	third-party plugin authors. Formerly, many of them were exposed via the `extras/` API, which
	is now deprecated.

	Most of these are internal, and the APIs are not thoroughly documented. You will
	most likely need to read the source code to understand how they work.

	{% include alert/start.html variant="warning"%}
	{% markdown %}

	Warning: you are entering a semver-free zone.

	In contrast to the presets and plugins listed above, **none of the following packages
	follow semver**. Their versions are pinned to PouchDB's, and may change at any time
	without warning. You are strongly recommended to use exact versions when installing these packages.

	{% endmarkdown %}
	{% include alert/end.html%}

	### pouchdb-abstract-mapreduce

	The underlying logic for secondary indexes, as expressed in both `pouchdb-mapreduce` and `pouchdb-find`. Both packages use this package under the hood.

	#### Example usage

	```bash
	npm install --save-exact pouchdb-abstract-mapreduce
	```

	### pouchdb-adapter-utils

	Utilities for PouchDB adapters.

	#### Example usage

	```bash
	npm install --save-exact pouchdb-adapter-utils
	```

	### pouchdb-ajax

	PouchDB's `ajax()` function.

	#### Example usage

	```bash
	npm install --save-exact pouchdb-ajax
	```

	### pouchdb-binary-utils

	Utilities for operating on binary strings and Buffers/Blobs.

	#### Example usage

	```bash
	npm install --save-exact pouchdb-binary-utils
	```

	### pouchdb-checkpointer

	Tool to write a checkpoint, e.g. during replication.

	#### Example usage

	```bash
	npm install --save-exact pouchdb-checkpointer
	```

	### pouchdb-collate

	Collation functions for PouchDB map/reduce.

	#### Example usage

	```bash
	npm install --save-exact pouchdb-collate
	```

	### pouchdb-collections

	ES6 shims for Map and Set as used in PouchDB.

	#### Example usage

	```bash
	npm install --save-exact pouchdb-collections
	```

	### pouchdb-debug

	The `PouchDB.debug()` API, expressed as a separate plugin. May eventually be removed from PouchDB core.

	#### Example usage

	```bash
	npm install --save-exact pouchdb-debug
	```

	### pouchdb-errors

	Errors exposed by PouchDB.

	#### Example usage

	```bash
	npm install --save-exact pouchdb-errors
	```

	### pouchdb-generate-replication-id

	Function to generate a replication ID to mark progress during replications.

	#### Example usage

	```bash
	npm install --save-exact pouchdb-generate-replication-id
	```

	### pouchdb-json

	Utilities for safely stringifying and parsing JSON.

	#### Example usage

	```bash
	npm install --save-exact pouchdb-json
	```

	### pouchdb-mapreduce-utils

	Utilities used by `pouchdb-mapreduce`.

	#### Example usage

	```bash
	npm install --save-exact pouchdb-mapreduce-utils
	```

	### pouchdb-md5

	Utilities for calculating MD5 checksums.

	#### Example usage

	```bash
	npm install --save-exact pouchdb-md5
	```

	### pouchdb-merge

	PouchDB's CouchDB-style document merge algorithm.

	#### Example usage

	```bash
	npm install --save-exact pouchdb-merge
	```

	### pouchdb-promise

	A `Promise` object, polyfilled using `lie` if Promises aren't available globally.

	#### Example usage

	```bash
	npm install --save-exact pouchdb-promise
	```

	### pouchdb-selector-core

	The core Mango selector logic, which allows the selector to be used both by `pouchdb-find` and for filtering/replication.

	#### Example usage

	```bash
	npm install --save-exact pouchdb-selector-core
	```

	### pouchdb-utils

	A potpourri of miscellaneous utilities used by PouchDB and its sub-packages.

	#### Example usage

	```bash
	npm install --save-exact pouchdb-utils
	```

	### sublevel-pouchdb

	Fork of [level-sublevel](https://github.com/dominictarr/level-sublevel)
	with ony the subset of the API that PouchDB uses.

	#### Example usage

	```bash
	npm install --save-exact sublevel-pouchdb
	```