adobe
- About
- Features
- ESM/CJS support
- Installation
- API
- Common Usage Examples
- Advanced Usage Examples
- More examples
- Development
- Acknowledgement
- License
About
@adobe/fetch in general adheres to the Fetch API Specification, implementing a subset of the API. However, there are some notable deviations:
Response.bodyreturns a Node.js Readable stream.Response.blob()is not implemented. UseResponse.buffer()instead.Response.formData()is not implemented.- Cookies are not stored by default. However, cookies can be extracted and passed by manipulating request and response headers.
- The following values of the
fetch()optioncacheare supported:'default'(the implicit default) and'no-store'. All other values are currently ignored. - The following
fetch()options are ignored due to the nature of Node.js and since@adobe/fetchdoesn't have the concept of web pages:mode,referrer,referrerPolicy,integrityandcredentials. - The
fetch()optionkeepaliveis not supported. But you can use theh1.keepAlivecontext option, as demonstrated here.
@adobe/fetch also supports the following non-spec extensions:
Response.buffer()returns a Node.jsBuffer.Response.urlcontains the final url when following redirects.- The
bodythat can be sent in aRequestcan also be aReadableNode.js stream, aBuffer, a string or a plain object. - There are no forbidden header names.
- The
Responseobject has an extra propertyhttpVersionwhich is one of'1.0','1.1'or'2.0', depending on what was negotiated with the server. - The
Responseobject has an extra propertyfromCachewhich determines whether the response was retrieved from cache. - The
Responseobject has an extra propertydecodedwhich determines whether the response body was automatically decoded (see Fetch optiondecodebelow). Response.headers.plain()returns the headers as a plain object.Response.headers.raw()returns the internal/raw representation of the headers where e.g. theSet-Cokkieheader is represented with an array of strings value.- The Fetch option
followallows to limit the number of redirects to follow (default:20). - The Fetch option
compressenables transparent gzip/deflate/br content encoding (default:true). - The Fetch option
decodeenables transparent gzip/deflate/br content decoding (default:true).
Note that non-standard Fetch options have been aligned with node-fetch where appropriate.
Features
- <input checked="" disabled="" type="checkbox"> supports reasonable subset of the standard Fetch specification
- <input checked="" disabled="" type="checkbox"> Transparent handling of HTTP/1(.1) and HTTP/2 connections
- <input checked="" disabled="" type="checkbox"> RFC 7234 compliant cache
- <input checked="" disabled="" type="checkbox"> Support
gzip/deflate/brcontent encoding - <input checked="" disabled="" type="checkbox"> HTTP/2 request and response multiplexing support
- <input checked="" disabled="" type="checkbox"> HTTP/2 Server Push support (transparent caching and explicit listener support)
- <input checked="" disabled="" type="checkbox"> overridable User-Agent
- <input checked="" disabled="" type="checkbox"> low-level HTTP/1.* agent/connect options support (e.g.
keepAlive,rejectUnauthorized)
ESM/CJS support
This package is native ESM and no longer provides CommonJS exports. Use 3.x version if you still need to use this package with CommonJS.
Installation
Note:
As of v4 Node version >= 14.16 is required.
$ npm install @adobe/fetchAPI
Apart from the standard Fetch API
fetch()RequestResponseHeadersBody
@adobe/fetch exposes the following non-spec extensions:
context()- creates a new customized API contextreset()- resets the current API context, i.e. closes pending sessions/sockets, clears internal caches, etc ...onPush()- registers an HTTP/2 Server Push listeneroffPush()- deregisters a listener previously registered withonPush()clearCache()- clears the HTTP cache (cached responses)cacheStats()- returns cache statisticsnoCache()- creates a customized API context with disabled caching (convenience)h1()- creates a customized API context with enforced HTTP/1.1 protocol (convenience)keepAlive()- creates a customized API context with enforced HTTP/1.1 protocol and persistent connections (convenience)h1NoCache()- creates a customized API context with disabled caching and enforced HTTP/1.1 protocol (convenience)keepAliveNoCache()- creates a customized API context with disabled caching and enforced HTTP/1.1 protocol with persistent connections (convenience)createUrl()- creates a URL with query parameters (convenience)timeoutSignal()- ceates a timeout signal (convenience)
Context
An API context allows to customize certain aspects of the implementation and provides isolation of internal structures (session caches, HTTP cache, etc.) per API context.
The following options are supported:
interface ContextOptions {
/**
* Value of `user-agent` request header
* @default 'adobe-fetch/<version>'
*/
userAgent?: string;
/**
* The maximum total size of the cached entries (in bytes). 0 disables caching.
* @default 100 * 1024 * 1024
*/
maxCacheSize?: number;
/**
* The protocols to be negotiated, in order of preference
* @default [ALPN_HTTP2, ALPN_HTTP1_1, ALPN_HTTP1_0]
*/
alpnProtocols?: ReadonlyArray< ALPNProtocol >;
/**
* How long (in milliseconds) should ALPN information be cached for a given host?
* @default 60 * 60 * 1000
*/
alpnCacheTTL?: number;
/**
* (HTTPS only, applies to HTTP/1.x and HTTP/2)
* If not false, the server certificate is verified against the list of supplied CAs. An 'error' event is emitted if verification fails; err.code contains the OpenSSL error code.
* @default true
*/
rejectUnauthorized?: boolean;
/**
* Maximum number of ALPN cache entries
* @default 100
*/
alpnCacheSize?: number;
h1?: Http1Options;
h2?: Http2Options;
};
interface Http1Options {
/**
* Keep sockets around in a pool to be used by other requests in the future.
* @default false
*/
keepAlive?: boolean;
/**
* When using HTTP KeepAlive, how often to send TCP KeepAlive packets over sockets being kept alive.
* Only relevant if keepAlive is set to true.
* @default 1000
*/
keepAliveMsecs?: number;
/**
* (HTTPS only)
* If not false, the server certificate is verified against the list of supplied CAs. An 'error' event is emitted if verification fails; err.code contains the OpenSSL error code.
* @default true
*/
rejectUnauthorized?: boolean;
/**
* (HTTPS only)
* Maximum number of TLS cached sessions. Use 0 to disable TLS session caching.
* @default 100
*/
maxCachedSessions?: number;
}
interface Http2Options {
/**
* Max idle time in milliseconds after which a session will be automatically closed.
* @default 5 * 60 * 1000
*/
idleSessionTimeout?: number;
/**
* Enable HTTP/2 Server Push?
* @default true
*/
enablePush?: boolean;
/**
* Max idle time in milliseconds after which a pushed stream will be automatically closed.
* @default 5000
*/
pushedStreamIdleTimeout?: number;
/**
* (HTTPS only)
* If not false, the server certificate is verified against the list of supplied CAs. An 'error' event is emitted if verification fails; err.code contains the OpenSSL error code.
* @default true
*/
rejectUnauthorized?: boolean;
};Common Usage Examples
Access Response Headers and other Meta data
import { fetch } from '@adobe/fetch';
const resp = await fetch('https://httpbin.org/get');
console.log(resp.ok);
console.log(resp.status);
console.log(resp.statusText);
console.log(resp.httpVersion);
console.log(resp.headers.plain());
console.log(resp.headers.get('content-type'));Fetch JSON
import { fetch } from '@adobe/fetch';
const resp = await fetch('https://httpbin.org/json');
const jsonData = await resp.json();Fetch text data
import { fetch } from '@adobe/fetch';
const resp = await fetch('https://httpbin.org/');
const textData = await resp.text();Fetch binary data
import { fetch } from '@adobe/fetch';
const resp = await fetch('https://httpbin.org//stream-bytes/65535');
const imageData = await resp.buffer();Specify a timeout for a fetch operation
Using timeoutSignal(ms) non-spec extension:
import { fetch, timeoutSignal, AbortError } from '@adobe/fetch';
const signal = timeoutSignal(1000);
try {
const resp = await fetch('https://httpbin.org/json', { signal });
const jsonData = await resp.json();
} catch (err) {
if (err instanceof AbortError) {
console.log('fetch timed out after 1s');
}
} finally {
// avoid pending timers which prevent node process from exiting
signal.clear();
}Using AbortController:
import { fetch, AbortController, AbortError } from '@adobe/fetch';
const controller = new AbortController();
const timerId = setTimeout(() => controller.abort(), 1000);
const { signal } = controller;
try {
const resp = await fetch('https://httpbin.org/json', { signal });
const jsonData = await resp.json();
} catch (err) {
if (err instanceof AbortError) {
console.log('fetch timed out after 1s');
}
} finally {
// avoid pending timers which prevent node process from exiting
clearTimeout(timerId);
}Stream an image
import { createWriteStream } from 'fs';
import { fetch } from '@adobe/fetch';
const resp = await fetch('https://httpbin.org/image/jpeg');
resp.body.pipe(createWriteStream('saved-image.jpg'));Post JSON
import { fetch } from '@adobe/fetch';
const method = 'POST';
const body = { foo: 'bar' };
const resp = await fetch('https://httpbin.org/post', { method, body });Post JPEG image
import { createReadStream } from 'fs';
import { fetch } from '@adobe/fetch';
const method = 'POST';
const body = createReadStream('some-image.jpg');
const headers = { 'content-type': 'image/jpeg' };
const resp = await fetch('https://httpbin.org/post', { method, body, headers });Post form data
import { FormData, Blob, File } from 'formdata-node'; // spec-compliant implementations
import { fileFromPath } from 'formdata-node/file-from-path'; // helper for creating File instance from disk file
import { fetch } from '@adobe/fetch';
const method = 'POST';
const fd = new FormData();
fd.set('field1', 'foo');
fd.set('field2', 'bar');
fd.set('blob', new Blob([0x68, 0x65, 0x6c, 0x69, 0x78, 0x2d, 0x66, 0x65, 0x74, 0x63, 0x68]));
fd.set('file', new File(['File content goes here'], 'file.txt'));
fd.set('other_file', await fileFromPath('/foo/bar.jpg', 'bar.jpg', { type: 'image/jpeg' }));
const resp = await fetch('https://httpbin.org/post', { method, body: fd });GET with query parameters object
import { createUrl, fetch } from '@adobe/fetch';
const qs = {
fake: 'dummy',
foo: 'bar',
rumple: "stiltskin",
};
const resp = await fetch(createUrl('https://httpbin.org/json', qs));or using URLSearchParams:
import { fetch } from '@adobe/fetch';
const body = new URLSearchParams({
fake: 'dummy',
foo: 'bar',
rumple: "stiltskin",
});
const resp = await fetch('https://httpbin.org/json', { body });Cache
Responses of GET and HEAD requests are by default cached, according to the rules of RFC 7234:
import { fetch } from '@adobe/fetch';
const url = 'https://httpbin.org/cache/60'; // -> max-age=60 (seconds)
// send initial request, priming cache
let resp = await fetch(url);
assert(resp.ok);
assert(!resp.fromCache);
// re-send request and verify it's served from cache
resp = await fetch(url);
assert(resp.ok);
assert(resp.fromCache);You can disable caching per request with the cache: 'no-store' option:
import { fetch } from '@adobe/fetch';
const resp = await fetch('https://httbin.org/', { cache: 'no-store' });
assert(resp.ok);
assert(!resp.fromCache);You can disable caching entirely:
import { noCache } from '@adobe/fetch';
const { fetch } = noCache();Advanced Usage Examples
HTTP/2 Server Push
Note that pushed resources will be automatically and transparently added to the cache. You can however add a listener which will be notified on every pushed (and cached) resource.
import { fetch, onPush } from '@adobe/fetch';
onPush((url, response) => console.log(`received server push: ${url} status ${response.status}`));
const resp = await fetch('https://nghttp2.org');
console.log(`Http version: ${resp.httpVersion}`);Use h2c (http2 cleartext w/prior-knowledge) protocol
import { fetch } from '@adobe/fetch';
const resp = await fetch('http2://nghttp2.org');
console.log(`Http version: ${resp.httpVersion}`);Force HTTP/1(.1) protocol
import { h1 } from '@adobe/fetch';
const { fetch } = h1();
const resp = await fetch('https://nghttp2.org');
console.log(`Http version: ${resp.httpVersion}`);HTTP/1.1 Keep-Alive
import { keepAlive } from '@adobe/fetch';
const { fetch } = keepAlive();
const resp = await fetch('https://httpbin.org/status/200');
console.log(`Connection: ${resp.headers.get('connection')}`); // -> keep-aliveExtract Set-Cookie Header
Unlike browsers, you can access raw Set-Cookie headers manually using Headers.raw(). This is an @adobe/fetch only API.
import { fetch } from '@adobe/fetch';
const resp = await fetch('https://httpbin.org/cookies/set?a=1&b=2');
// returns an array of values, instead of a string of comma-separated values
console.log(resp.headers.raw()['set-cookie']);Self-signed Certificates
import { context } from '@adobe/fetch';
const { fetch } = context({ rejectUnauthorized: false });
const resp = await fetch('https://localhost:8443/'); // a server using a self-signed certificateSet cache size limit
import { context } from '@adobe/fetch';
const { fetch } = context({
maxCacheSize: 100 * 1024, // 100kb (Default: 100mb)
});
let resp = await fetch('https://httpbin.org/bytes/60000'); // ~60kb response
resp = await fetch('https://httpbin.org/bytes/50000'); // ~50kb response
console.log(cacheStats());Disable caching
import { noCache } from '@adobe/fetch';
const { fetch } = noCache();
let resp = await fetch('https://httpbin.org/cache/60'); // -> max-age=60 (seconds)
// re-fetch
resp = await fetch('https://httpbin.org/cache/60');
assert(!resp.fromCache);Set a custom user agent
import { context } from '@adobe/fetch';
const { fetch } = context({
userAgent: 'custom-fetch'
});
const resp = await fetch('https://httpbin.org//user-agent');
const json = await resp.json();
console.log(json['user-agent']);More examples
More example code can be found in the test source files.
Development
Build
$ npm installTest
$ npm testLint
$ npm run lintTroubleshooting
You can enable @adobe/fetch low-level debug console output by setting the DEBUG environment variable to adobe/fetch*, e.g.:
$ DEBUG=adobe/fetch* node test.jsThis will produce console outout similar to:
...
adobe/fetch:core established TLS connection: #48 (www.nghttp2.org) +2s
adobe/fetch:core www.nghttp2.org -> h2 +0ms
adobe/fetch:h2 reusing socket #48 (www.nghttp2.org) +2s
adobe/fetch:h2 GET www.nghttp2.org/httpbin/user-agent +0ms
adobe/fetch:h2 session https://www.nghttp2.org established +1ms
adobe/fetch:h2 caching session https://www.nghttp2.org +0ms
adobe/fetch:h2 session https://www.nghttp2.org remoteSettings: {"headerTableSize":8192,"enablePush":true,"initialWindowSize":1048576,"maxFrameSize":16384,"maxConcurrentStreams":100,"maxHeaderListSize":4294967295,"maxHeaderSize":4294967295,"enableConnectProtocol":true} +263ms
adobe/fetch:h2 session https://www.nghttp2.org localSettings: {"headerTableSize":4096,"enablePush":true,"initialWindowSize":65535,"maxFrameSize":16384,"maxConcurrentStreams":4294967295,"maxHeaderListSize":4294967295,"maxHeaderSize":4294967295,"enableConnectProtocol":false} +0ms
adobe/fetch:h2 session https://www.nghttp2.org closed +6ms
adobe/fetch:h2 discarding cached session https://www.nghttp2.org +0ms
... Additionally, you can enable Node.js low-level debug console output by setting the NODE_DEBUG environment variable appropriately, e.g.
$ export NODE_DEBUG=http*,stream*
$ export DEBUG=adobe/fetch*
$ node test.jsNote: this will flood the console with highly verbose debug output.
Acknowledgement
Thanks to node-fetch and github/fetch for providing a solid implementation reference.