Streams API | Web API

在此页

概念和用法
Stream interfaces
范例
规范
浏览器兼容性
另请参阅
相关话题

这是实验性技术
检查浏览器兼容性表格要小心谨慎在生产中使用这之前。

The Streams API allows JavaScript to programmatically access streams of data received over the network and process them as desired by the developer.

概念和用法

Streaming involves breaking a resource that you want to receive over a network down into small chunks, then processing it bit by bit. This is something browsers do anyway when receiving assets to be shown on webpages — videos buffer and more is gradually available to play, and sometimes you'll see images display gradually as more is loaded.

But this has never been available to JavaScript before. Previously, if we wanted to process a resource of some kind (be it a video, or a text file, etc.), we'd have to download the entire file, wait for it to be deserialized into a suitable format, then process the whole lot after it is fully received.

With Streams being available to JavaScript, this all changes — you can now start processing raw data with JavaScript bit by bit as soon as it is available on the client-side, without needing to generate a buffer, string, or blob.

There are more advantages too — you can detect when streams start or end, chain streams together, handle errors and cancel streams as required, and react to the speed of the stream is being read at.

The basic usage of Streams hinges around making responses available as streams. For example, the response Body returned by a successful fetch request can be exposed as a ReadableStream , and you can then read it using a reader created with ReadableStream.getReader() , cancel it with ReadableStream.cancel() ，等。

More complicated uses involve creating your own stream using the ReadableStream() constructor, for example to process data inside a service worker .

You can also write data to streams using WritableStream .

注意 : You can find a lot more details about the theory and practice of streams in our articles — Streams API concepts , Using readable streams ，和 Using writable streams .

Stream interfaces

Readable streams

ReadableStream: Represents a readable stream of data. It can be used to handle response streams of the 抓取 API , or developer-defined streams (e.g. a custom ReadableStream() 构造函数)。
ReadableStreamDefaultReader
ReadableStreamDefaultController: Represents a controller allowing control of a ReadableStream 's state and internal queue. Default controllers are for streams that are not byte streams.

Writable streams

WritableStream
WritableStreamDefaultWriter
WritableStreamDefaultController: Represents a controller allowing control of a WritableStream 's state. When constructing a WritableStream , the underlying sink is given a corresponding WritableStreamDefaultController instance to manipulate.

Related stream APIs and operations

ByteLengthQueuingStrategy
CountQueuingStrategy

Extensions to other APIs

Request: 当新 Request object is constructed, you can pass it a ReadableStream 在 body property of its RequestInit dictionary. This Request could then be passed to a WindowOrWorkerGlobalScope.fetch() to commence fetching the stream.
Body: The response Body returned by a successful fetch request is exposed by default as a ReadableStream , and can have a reader attached to it, etc.

ByteStream-related interfaces

重要 : these are not implemented anywhere as yet, and questions have been raised as to whether the spec details are in a finished enough state for them to be implemented. This may change over time.

ReadableStreamBYOBReader: Represents a BYOB ("bring your own buffer") reader that can be used to read stream data supplied by the developer (e.g. a custom ReadableStream() 构造函数)。
ReadableByteStreamController: Represents a controller allowing control of a ReadableStream 's state and internal queue. Byte stream controllers are for byte streams.
ReadableStreamBYOBRequest: Represents a pull into request in a ReadableByteStreamController .

范例

We have created a directory of examples to go along with the Streams API documentation — see mdn/dom-examples/streams . The examples are as follows:

Simple stream pump : This example shows how to consume a ReadableStream and pass its data to another.
Grayscale a PNG : This example shows how a ReadableStream of a PNG can be turned into grayscale.
Simple random stream : This example shows how to use a custom stream to generate random strings, enqueue them as chunks, and then read them back out again.
Simple tee example : This example extends the Simple random stream example, showing how a stream can be teed and both resulting streams can be read independently.
Simple writer : This example shows how to to write to a writable stream, then decode the stream and write the contents to the UI.
Unpack chunks of a PNG : This example shows how pipeThrough() can be used to transform a ReadableStream into a stream of other data types by transforming a data of a PNG file into a stream of PNG chunks.

Examples from other developers:

Progress Indicators with Streams, Service Workers, & Fetch .

规范

规范	状态	注释
流	实时标准	初始定义。

浏览器兼容性

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

ReadableStream

更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`ReadableStream`	Chrome 43	Edge 14	Firefox 65 65 57 Disabled Disabled From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true` ) 和 preference (needs to be set to ). To change preferences in Firefox, visit about:config.	IE No	Opera 30	Safari 10.1	WebView Android 43	Chrome Android 43	Firefox Android 65 65 57 Disabled Disabled From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true` ) 和 preference (needs to be set to ). To change preferences in Firefox, visit about:config.	Opera Android 30	Safari iOS 10.3	Samsung Internet Android 4.0
`ReadableStream()` 构造函数	Chrome 43	Edge 79	Firefox 65 65 57 Disabled Disabled From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true` ) 和 preference (needs to be set to ). To change preferences in Firefox, visit about:config.	IE No	Opera 30	Safari 10.1	WebView Android 43	Chrome Android 43	Firefox Android 65 65 57 Disabled Disabled From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true` ) 和 preference (needs to be set to ). To change preferences in Firefox, visit about:config.	Opera Android 30	Safari iOS 10.3	Samsung Internet Android 4.0
`cancel`	Chrome 43	Edge 14	Firefox 65 65 57 Disabled Disabled From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true` ) 和 preference (needs to be set to ). To change preferences in Firefox, visit about:config.	IE No	Opera 30	Safari 10.1	WebView Android 43	Chrome Android 43	Firefox Android 65 65 57 Disabled Disabled From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true` ) 和 preference (needs to be set to ). To change preferences in Firefox, visit about:config.	Opera Android 30	Safari iOS 10.3	Samsung Internet Android 4.0
`getReader`	Chrome 43	Edge 14	Firefox 65 65 57 Disabled Disabled From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true` ) 和 preference (needs to be set to ). To change preferences in Firefox, visit about:config.	IE No	Opera 30	Safari 10.1	WebView Android 43	Chrome Android 43	Firefox Android 65 65 57 Disabled Disabled From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true` ) 和 preference (needs to be set to ). To change preferences in Firefox, visit about:config.	Opera Android 30	Safari iOS 10.3	Samsung Internet Android 4.0
`locked`	Chrome 43	Edge 14	Firefox 65 65 57 Disabled Disabled From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true` ) 和 preference (needs to be set to ). To change preferences in Firefox, visit about:config.	IE No	Opera 30	Safari 10.1	WebView Android 43	Chrome Android 43	Firefox Android 65 65 57 Disabled Disabled From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true` ) 和 preference (needs to be set to ). To change preferences in Firefox, visit about:config.	Opera Android 30	Safari iOS 10.3	Samsung Internet Android 4.0
`pipeThrough`	Chrome 59	Edge 79	Firefox No	IE No	Opera 46	Safari 10.1	WebView Android 59	Chrome Android 59	Firefox Android No	Opera Android 43	Safari iOS 10.3	Samsung Internet Android 7.0
`pipeTo`	Chrome 59	Edge 79	Firefox No	IE No	Opera 46	Safari 10.1	WebView Android 59	Chrome Android 59	Firefox Android No	Opera Android 43	Safari iOS 10.3	Samsung Internet Android 7.0
`tee`	Chrome 43	Edge 79	Firefox 65 65 57 Disabled Disabled From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true` ) 和 preference (needs to be set to ). To change preferences in Firefox, visit about:config.	IE No	Opera 30	Safari 10.1	WebView Android 43	Chrome Android 43	Firefox Android 65 65 57 Disabled Disabled From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true` ) 和 preference (needs to be set to ). To change preferences in Firefox, visit about:config.	Opera Android 30	Safari iOS 10.3	Samsung Internet Android 4.0

图例

完整支持
不支持
实验。期望将来行为有所改变。
用户必须明确启用此特征。

WritableStream