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Streaming data with async generators
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| async function returnWait<T>(timeToDelay: number, value: T): Promise<T> { | |
| return new Promise((resolve) => setTimeout(() => resolve(value), 1000)); | |
| } | |
| const encoder = new TextEncoder(); | |
| async function* iterator() { | |
| let index = 0; | |
| if (index === 0) { | |
| const thing = await returnWait(1000, { hello: 'first' }); | |
| yield encoder.encode('[' + JSON.stringify(thing)); | |
| ++index; | |
| } | |
| while (index !== 1000) { | |
| const thing = await returnWait(1000, { hello: 'middle' }); | |
| index++; | |
| if (index === 1000) { | |
| yield encoder.encode(JSON.stringify(thing) + ']'); | |
| } else { | |
| yield encoder.encode(JSON.stringify(thing)); | |
| } | |
| } | |
| } | |
| const generator = iterator(); | |
| const streamResponse = new ReadableStream({ | |
| async pull(controller) { | |
| const { value, done } = await generator.next(); | |
| if (done) { | |
| controller.close(); | |
| } else { | |
| controller.enqueue(value); | |
| } | |
| }, | |
| }); | |
| return new Response(streamResponse, { | |
| status: 200, | |
| headers: { | |
| 'Content-Type': 'application/json', | |
| }, | |
| }); |
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