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• 关键概念和用法
• 接口
• 范例
• 规范
• 另请参阅
• 相关话题

IndexedDB is a low-level API for client-side storage of significant amounts of structured data, including files/blobs. This API uses indexes to enable high-performance searches of this data. While Web 存储 可用于存储少量数据，但对于存储大量结构化数据却不那么有用。IndexedDB 提供解决方案。这是 MDN 的 IndexedDB 覆盖范围的主登录页面 — 这里提供完整 API 参考和用法指南，浏览器支持细节及一些关键概念解释的链接。

注意： 此特征可用于 Web 工作者 .

注意 ：IndexedDB API 功能强大，但对于简单情况而言似乎太复杂。若您偏好简单 API，可尝试库如 localForage , dexie.js , ZangoDB , PouchDB , idb , idb-keyval , JsStore and lovefield that make IndexedDB more programmer-friendly.

关键概念和用法

IndexedDB is a transactional database system, like an SQL-based RDBMS. However, unlike SQL-based RDBMSes, which use fixed-column tables, IndexedDB is a JavaScript-based object-oriented database. IndexedDB lets you store and retrieve objects that are indexed with a key ; any objects supported by the structured clone algorithm can be stored. You need to specify the database schema, open a connection to your database, and then retrieve and update data within a series of transactions .

• Read more about the Concepts behind IndexedDB .
• Learn to use IndexedDB asynchronously from first principles with our 使用 IndexedDB guide.
• Combine IndexedDB for storing data offline with Service Workers for storing assets offline, as outlined in Making PWAs work offline with Service workers .

注意 : Like most web storage solutions, IndexedDB follows a same-origin policy . So while you can access stored data within a domain, you cannot access data across different domains.

同步和异步

Operations performed using IndexedDB are done asynchronously, so as not to block applications. IndexedDB originally included both synchronous and asynchronous APIs. The synchronous API was intended for use only with Web 工作者 but was removed from the spec because it was unclear whether it was needed. However, the synchronous API may be reintroduced if there is enough demand from web developers.

存储限制和驱逐准则

There are a number of web technologies that store data of one kind or another on the client side (i.e. on your local disk). IndexedDB is most commonly talked about. The process by which the browser works out how much space to allocate to web data storage and what to delete when that limit is reached is not simple, and differs between browsers. 浏览器存储限制和驱逐准则 attempts to explain how this works, at least in the case of Firefox.

接口

要访问数据库，调用 open() 在 indexedDB attribute of a window object. This method returns an IDBRequest object; asynchronous operations communicate to the calling application by firing events on IDBRequest 对象。

连接到数据库

IDBEnvironment

Provides access to IndexedDB functionality. It is implemented by the window and worker objects. This interface isn't part of the 2.0 specification.

IDBFactory

Provides access to a database. This is the interface implemented by the global object indexedDB and is therefore the entry point for the API.

IDBOpenDBRequest

表示打开数据库的请求。

IDBDatabase

Represents a connection to a database. It's the only way to get a transaction on the database.

检索和修改数据

IDBTransaction

Represents a transaction. You create a transaction on a database, specify the scope (such as which object stores you want to access), and determine the kind of access (read only or readwrite) that you want.

IDBRequest

Generic interface that handles database requests and provides access to results.

IDBObjectStore

Represents an object store that allows access to a set of data in an IndexedDB database, looked up via primary key.

IDBIndex

Also allows access to a subset of data in an IndexedDB database, but uses an index to retrieve the record(s) rather than the primary key. This is sometimes faster than using IDBObjectStore .

IDBCursor

遍历对象存储和索引。

IDBCursorWithValue

Iterates over object stores and indexes and returns the cursor's current value.

IDBKeyRange

Defines a key range that can be used to retrieve data from a database in a certain range.

IDBLocaleAwareKeyRange

Defines a key range that can be used to retrieve data from a database in a certain range, sorted according to the rules of the locale specified for a certain index (see createIndex() 's optionalParameters .). This interface isn't part of the 2.0 specification.

自定义事件接口

This specification fires events with the following custom interface:

IDBVersionChangeEvent

IDBVersionChangeEvent interface indicates that the version of the database has changed, as the result of an IDBOpenDBRequest.onupgradeneeded event handler function.

过时接口

An early version of the specification also defined the following, now removed, interfaces. They are still documented in case you need to update previously written code:

IDBVersionChangeRequest

Represents a request to change the version of a database. The way to change the version of the database has since changed (by calling IDBFactory.open without also calling IDBDatabase.setVersion ), and the interface IDBOpenDBRequest now has the functionality of the removed IDBVersionChangeRequest .

IDBDatabaseException

Represents exception conditions that can be encountered while performing database operations.

IDBTransactionSync

同步版本的 IDBTransaction .

IDBObjectStoreSync

同步版本的 IDBObjectStore .

IDBIndexSync

同步版本的 IDBIndex .

IDBFactorySync

同步版本的 IDBFactory .

IDBEnvironmentSync

同步版本的 IDBEnvironment .

IDBDatabaseSync

同步版本的 IDBDatabase .

IDBCursorSync

同步版本的 IDBCursor .

范例

• eLibri: A powerful library and eBook reader application, written by Marco Castelluccio, winner of the IndexedDB Mozilla DevDerby.
• 待办通知 ( 实时查看范例 ): The reference application for the examples in the reference docs.
• 以 IndexedDB 存储图像和文件

规范

规范	状态	注释
索引数据库 API 草案	推荐
索引数据库 API 2.0	推荐	初始定义

另请参阅

• localForage : A Polyfill providing a simple name:value syntax for client-side data storage, which uses IndexedDB in the background, but falls back to WebSQL and then localStorage in browsers that don't support IndexedDB.
• Dexie.js : A wrapper for IndexedDB that allows much faster code development via nice, simple syntax.
• ZangoDB : A MongoDB-like interface for IndexedDB that supports most of the familiar filtering, projection, sorting, updating and aggregation features of MongoDB.
• JsStore : An IndexedDB wrapper with SQL like syntax.
• MiniMongo : A client-side in-memory mongodb backed by localstorage with server sync over http. MiniMongo is used by MeteorJS.
• PouchDB : A client-side implementation of CouchDB in the browser using IndexedDB
• idb : A tiny (~1.15k) library that mostly mirrors the IndexedDB API, but with small improvements that make a big difference to usability.
• idb-keyval : A super-simple-small (~600B) promise-based keyval store implemented with IndexedDB
• sifrr-storage: A small (~2kB) promise based library for client side key-value storage. Works with IndexedDB, localStorage, WebSQL, Cookies. Can automatically use supported storage available based on priority.
• lovefield : Lovefield is a relational database for web apps. Written in JavaScript, works cross-browser. Provides SQL-like APIs that are fast, safe, and easy to use.

元数据

• 最后修改： May 3, 2020

相关话题

1. IndexedDB API
2. 指南

   1. 使用 IndexedDB
   2. 基本概念
   3. 浏览器存储限制和驱逐准则
   4. 校验当由于截止日期
3. 接口

   1. IDBCursor
   2. IDBCursorSync
   3. IDBCursorWithValue
   4. IDBDatabase
   5. IDBDatabaseException
   6. IDBDatabaseSync
   7. IDBEnvironment
   8. IDBEnvironmentSync
   9. IDBFactory
   10. IDBFactorySync
   11. IDBIndex
   12. IDBIndexSync
   13. IDBKeyRange
   14. IDBObjectStore
   15. IDBObjectStoreSync
   16. IDBOpenDBRequest
   17. IDBRequest
   18. IDBTransaction
   19. IDBTransactionSync
   20. IDBVersionChangeEvent
   21. IDBVersionChangeRequest