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| import * as utils from './utils.js'; | |
| /** | |
| * Convert a `Response` body containing Server Sent Events (SSE) into an Async Iterator that yields {@linkcode ServerSentEventMessage} objects. | |
| * | |
| * @see {@link https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events} | |
| * | |
| * @example | |
| * ```js | |
| * // Optional | |
| * let abort = new AbortController; | |
| * | |
| * // Manually fetch a Response | |
| * let res = await fetch('https://...', { | |
| * method: 'POST', | |
| * signal: abort.signal, | |
| * headers: { | |
| * 'api-key': 'token <value>', | |
| * 'content-type': 'application/json', | |
| * }, | |
| * body: JSON.stringify({ | |
| * stream: true, // <- hypothetical | |
| * // ... | |
| * }) | |
| * }); | |
| * | |
| * if (res.ok) { | |
| * let stream = events(res, abort.signal); | |
| * for await (let event of stream) { | |
| * console.log('<<', event.data); | |
| * } | |
| * } | |
| * ``` | |
| */ | |
| export async function* events(res, signal) { | |
| // TODO: throw error? | |
| if (!res.body) | |
| return; | |
| let iter = utils.stream(res.body); | |
| let line, reader = iter.getReader(); | |
| let event; | |
| for (;;) { | |
| if (signal && signal.aborted) { | |
| return reader.cancel(); | |
| } | |
| line = await reader.read(); | |
| if (line.done) | |
| return; | |
| if (!line.value) { | |
| if (event) | |
| yield event; | |
| event = undefined; | |
| continue; | |
| } | |
| let [field, value] = utils.split(line.value) || []; | |
| if (!field) | |
| continue; // comment or invalid | |
| if (field === 'data') { | |
| event ||= {}; | |
| event[field] = event[field] ? (event[field] + '\n' + value) : value; | |
| } | |
| else if (field === 'event') { | |
| event ||= {}; | |
| event[field] = value; | |
| } | |
| else if (field === 'id') { | |
| event ||= {}; | |
| event[field] = +value || value; | |
| } | |
| else if (field === 'retry') { | |
| event ||= {}; | |
| event[field] = +value || undefined; | |
| } | |
| } | |
| } | |
| /** | |
| * Convenience function that will `fetch` with the given arguments and, if ok, will return the {@linkcode events} async iterator. | |
| * | |
| * If the response is not ok (status 200-299), the `Response` is thrown. | |
| * | |
| * @example | |
| * ```js | |
| * // NOTE: throws `Response` if not 2xx status | |
| * let events = await stream('https://api.openai.com/...', { | |
| * method: 'POST', | |
| * headers: { | |
| * 'Authorization': 'Bearer <token>', | |
| * 'Content-Type': 'application/json', | |
| * }, | |
| * body: JSON.stringify({ | |
| * stream: true, | |
| * // ... | |
| * }) | |
| * }); | |
| * | |
| * for await (let event of events) { | |
| * console.log('<<', JSON.parse(event.data)); | |
| * } | |
| * ``` | |
| */ | |
| export async function stream(input, init) { | |
| let req = new Request(input, init); | |
| utils.fallback(req.headers, 'Accept', 'text/event-stream'); | |
| utils.fallback(req.headers, 'Content-Type', 'application/json'); | |
| let r = await fetch(req); | |
| if (!r.ok) | |
| throw r; | |
| return events(r, req.signal); | |
| } | |