Forked from harrishancock/streaming-responses-200.js
Created
December 3, 2021 06:04
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Cloudflare Workers streaming response bodies example with unconditional 200
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addEventListener('fetch', event => { | |
event.respondWith(fetchAndApply(event.request)) | |
}) | |
/** | |
* Make multiple requests, | |
* aggregate the responses and | |
* stream it back as a single response. | |
*/ | |
async function fetchAndApply(request) { | |
const requestInit = { | |
headers: { "Authorization": "XXXXXX" } | |
} | |
const fetches = [ | |
"https://api.coinbase.com/v2/prices/BTC-USD/spot", | |
"https://api.coinbase.com/v2/prices/ETH-USD/spot", | |
"https://api.coinbase.com/v2/prices/LTC-USD/spot" | |
].map(url => fetch(url, requestInit)) | |
// Create a pipe and stream the response bodies out | |
// as a JSON array. | |
let { readable, writable } = new TransformStream() | |
streamJsonResponseBodies(fetches, writable) | |
return new Response(readable) | |
} | |
async function streamJsonResponseBodies(fetches, writable) { | |
let writer = writable.getWriter() | |
let encoder = new TextEncoder() | |
await writer.write(encoder.encode("[\n")) | |
for (let i = 0; i < fetches.length; ++i) { | |
let response = await fetches[i] | |
if (i > 0) await writer.write(encoder.encode(",\n")) | |
await manualPipeTo(response.body.getReader(), writer) | |
} | |
await writer.write(encoder.encode("]")) | |
await writer.close() | |
} | |
async function manualPipeTo(reader, writer) { | |
while (true) { | |
const { done, value } = await reader.read() | |
if (done) break | |
await writer.write(value) | |
} | |
} |
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