Wrappers for built-in fetch() enabling killswitch, logging, concurrency limit and other features.
fetch is great, however, its usage in secure environments is complicated. The library makes it simple.
A standalone file micro-ftch.js is also available.
npm install micro-ftch
import { ftch, jsonrpc, replayable } from 'micro-ftch';
let enabled = false;
const net = ftch(fetch, {
killswitch: () => enabled,
log: (url, options) => console.log(url, options),
timeout: 5000,
concurrencyLimit: 10,
});
const res = await net('https://example.com');
// Composable
const rpc = jsonrpc(net, 'http://rpc_node/', {
headers: {},
batchSize: 20,
});
const res1 = await rpc.call('method', 'arg0', 'arg1');
const res2 = await rpc.callNamed('method', { arg0: '0', arg1: '1' }); // named arguments
const testRpc = replayable(rpc);
// Basic auth auto-parsing
await net('https://user:[email protected]/basic-auth/user/pwd');There are three wrappers over fetch():
ftch(fetch)- killswitch, logging, timeouts, concurrency limits, basic authjsonrpc(fetch)- batched JSON-RPC functionalityreplayable(fetch)- log & replay network requests without actually calling network code.
Basic wrapper over fetch().
When kill-switch is enabled, all requests will throw an error. You can dynamically enable and disable it any any time.
let ENABLED = true;
const f = ftch(fetch, { killswitch: () => ENABLED });
f('http://localhost'); // ok
ENABLED = false;
f('http://localhost'); // throws
ENABLED = true;
f('http://localhost'); // okconst f = ftch(fetch, { log: (url, opts) => console.log('fetching', url, opts) });
f('http://url/'); // will print request information// browser and OS may have additional timeouts, we cannot override them
// a: per-request timeout
const f = ftch(fetch);
const res = await f('http://url/', { timeout: 1000 }); // throws if request takes more than one second
// b: timeout for all
const f = ftch(fetch, { timeout: 1000 });
const res = await f('http://url/'); // throws if request takes more than one secondAllows to not accidentally hit rate limits or do DoS.
// browser and OS may have additional limits, we cannot override them
const f = ftch(fetch, { concurrencyLimit: 1 });
const res = await Promise.all([f('http://url1/'), f('http://url2/')]); // these would be processed sequentiallyconst f = ftch(fetch);
const res = await f('https://user:[email protected]/basic-auth/user/pwd'); // supports basic auth!Supports batching multiple HTTP requests into one "Batched" JSON RPC HTTP request. Can massively speed-up when servers are single-threaded, has small per-user limits
const rpc = jsonrpc(fetch, 'http://rpc_node/', {
headers: {},
batchSize: 20,
});
const res = await rpc.call('method', 'arg0', 'arg1');
const res2 = await rpc.callNamed('method', { arg0: '0', arg1: '1' }); // named argumentsSmall utility to log & replay network requests in tests, without actually calling network code.
const ftch = ftch(fetch);
const replayCapture = replayable(ftch); // wraps fetch
await replayCapture('http://url/1'); // real network
await replayCapture('http://url/2');
const logs = replayCapture.export(); // Exports logs
// When logs provided - use cached version (faster)
const replayTest = replayable(ftch, JSON.parse(logs));
await replayTest('http://url/1'); // cached
await replayTest('http://url/2'); // cached
await replayTest('http://url/3'); // real network
// When done and everything is captured, turn on 'offline' mode to throw on network requests:
const replayTestOffline = replayable(ftch, JSON.parse(logs), {
offline: true,
});
await replayTest('http://url/1'); // cached
await replayTest('http://url/2'); // cached
await replayTest('http://url/3'); // throws!ftch() disables referrer by default by setting referrerPolicy: 'no-referrer'.
MIT (c) Paul Miller (https://paulmillr.com), see LICENSE file.