9.4 KiB
get-stream
Get a stream as a string, Buffer, ArrayBuffer or array
Features
- Works in any JavaScript environment (Node.js, browsers, etc.).
- Supports text streams, binary streams and object streams.
- Supports async iterables.
- Can set a maximum stream size.
- Returns partially read data when the stream errors.
- Fast.
Install
npm install get-stream
Usage
Node.js streams
import fs from 'node:fs';
import getStream from 'get-stream';
const stream = fs.createReadStream('unicorn.txt');
console.log(await getStream(stream));
/*
,,))))))));,
__)))))))))))))),
\|/ -\(((((''''((((((((.
-*-==//////(('' . `)))))),
/|\ ))| o ;-. '((((( ,(,
( `| / ) ;))))' ,_))^;(~
| | | ,))((((_ _____------~~~-. %,;(;(>';'~
o_); ; )))(((` ~---~ `:: \ %%~~)(v;(`('~
; ''''```` `: `:::|\,__,%% );`'; ~
| _ ) / `:|`----' `-'
______/\/~ | / /
/~;;.____/;;' / ___--,-( `;;;/
/ // _;______;'------~~~~~ /;;/\ /
// | | / ; \;;,\
(<_ | ; /',/-----' _>
\_| ||_ //~;~~~~~~~~~
`\_| (,~~
\~\
~~
*/
Web streams
import getStream from 'get-stream';
const {body: readableStream} = await fetch('https://example.com');
console.log(await getStream(readableStream));
Async iterables
import {opendir} from 'node:fs/promises';
import {getStreamAsArray} from 'get-stream';
const asyncIterable = await opendir(directory);
console.log(await getStreamAsArray(asyncIterable));
API
The following methods read the stream's contents and return it as a promise.
getStream(stream, options?)
stream
: stream.Readable
, ReadableStream
, or AsyncIterable<string | Buffer | ArrayBuffer | DataView | TypedArray>
options
: Options
Get the given stream
as a string.
getStreamAsBuffer(stream, options?)
Get the given stream
as a Node.js Buffer
.
import {getStreamAsBuffer} from 'get-stream';
const stream = fs.createReadStream('unicorn.png');
console.log(await getStreamAsBuffer(stream));
getStreamAsArrayBuffer(stream, options?)
Get the given stream
as an ArrayBuffer
.
import {getStreamAsArrayBuffer} from 'get-stream';
const {body: readableStream} = await fetch('https://example.com');
console.log(await getStreamAsArrayBuffer(readableStream));
getStreamAsArray(stream, options?)
Get the given stream
as an array. Unlike other methods, this supports streams of objects.
import {getStreamAsArray} from 'get-stream';
const {body: readableStream} = await fetch('https://example.com');
console.log(await getStreamAsArray(readableStream));
options
Type: object
maxBuffer
Type: number
Default: Infinity
Maximum length of the stream. If exceeded, the promise will be rejected with a MaxBufferError
.
Depending on the method, the length is measured with string.length
, buffer.length
, arrayBuffer.byteLength
or array.length
.
Errors
If the stream errors, the returned promise will be rejected with the error
. Any contents already read from the stream will be set to error.bufferedData
, which is a string
, a Buffer
, an ArrayBuffer
or an array depending on the method used.
import getStream from 'get-stream';
try {
await getStream(streamThatErrorsAtTheEnd('unicorn'));
} catch (error) {
console.log(error.bufferedData);
//=> 'unicorn'
}
Tips
Alternatives
If you do not need the maxBuffer
option, error.bufferedData
, nor browser support, you can use the following methods instead of this package.
streamConsumers.text()
import fs from 'node:fs';
import {text} from 'node:stream/consumers';
const stream = fs.createReadStream('unicorn.txt', {encoding: 'utf8'});
console.log(await text(stream))
streamConsumers.buffer()
import {buffer} from 'node:stream/consumers';
console.log(await buffer(stream))
streamConsumers.arrayBuffer()
import {arrayBuffer} from 'node:stream/consumers';
console.log(await arrayBuffer(stream))
readable.toArray()
console.log(await stream.toArray())
Array.fromAsync()
If your environment supports it:
console.log(await Array.fromAsync(stream))
Non-UTF-8 encoding
When all of the following conditions apply:
getStream()
is used (as opposed togetStreamAsBuffer()
orgetStreamAsArrayBuffer()
)- The stream is binary (not text)
- The stream's encoding is not UTF-8 (for example, it is UTF-16, hexadecimal, or Base64)
Then the stream must be decoded using a transform stream like TextDecoderStream
or b64
.
import getStream from 'get-stream';
const textDecoderStream = new TextDecoderStream('utf-16le');
const {body: readableStream} = await fetch('https://example.com');
console.log(await getStream(readableStream.pipeThrough(textDecoderStream)));
Blobs
getStreamAsArrayBuffer()
can be used to create Blobs.
import {getStreamAsArrayBuffer} from 'get-stream';
const stream = fs.createReadStream('unicorn.txt');
console.log(new Blob([await getStreamAsArrayBuffer(stream)]));
JSON streaming
getStreamAsArray()
can be combined with JSON streaming utilities to parse JSON incrementally.
import fs from 'node:fs';
import {compose as composeStreams} from 'node:stream';
import {getStreamAsArray} from 'get-stream';
import streamJson from 'stream-json';
import streamJsonArray from 'stream-json/streamers/StreamArray.js';
const stream = fs.createReadStream('big-array-of-objects.json');
console.log(await getStreamAsArray(
composeStreams(stream, streamJson.parser(), streamJsonArray.streamArray()),
));
Benchmarks
Node.js stream (100 MB, binary)
getStream()
: 142mstext()
: 139msgetStreamAsBuffer()
: 106msbuffer()
: 83msgetStreamAsArrayBuffer()
: 105msarrayBuffer()
: 81msgetStreamAsArray()
: 24msstream.toArray()
: 21ms
Node.js stream (100 MB, text)
getStream()
: 90mstext()
: 89msgetStreamAsBuffer()
: 127msbuffer()
: 192msgetStreamAsArrayBuffer()
: 129msarrayBuffer()
: 195msgetStreamAsArray()
: 89msstream.toArray()
: 90ms
Web ReadableStream (100 MB, binary)
getStream()
: 223mstext()
: 221msgetStreamAsBuffer()
: 182msbuffer()
: 153msgetStreamAsArrayBuffer()
: 171msarrayBuffer()
: 155msgetStreamAsArray()
: 83ms
Web ReadableStream (100 MB, text)
getStream()
: 141mstext()
: 139msgetStreamAsBuffer()
: 91msbuffer()
: 80msgetStreamAsArrayBuffer()
: 89msarrayBuffer()
: 81msgetStreamAsArray()
: 21ms
FAQ
How is this different from concat-stream
?
This module accepts a stream instead of being one and returns a promise instead of using a callback. The API is simpler and it only supports returning a string, Buffer
, an ArrayBuffer
or an array. It doesn't have a fragile type inference. You explicitly choose what you want. And it doesn't depend on the huge readable-stream
package.
Related
- get-stdin - Get stdin as a string or buffer
- into-stream - The opposite of this package