async-streamify/esm/receive/response.js

Stream and serialize nested promises and async iterables over HTTP, workers, etc

import { deserialize } from "./asyncObjectDeserializer.js";
/**
 * Deserializes a streaming NDJSON response into its original object form,
 * reconstructing promises and async iterables.
 *
 * @template T - The expected type of the deserialized object
 * @param response - The Response object containing the serialized NDJSON stream
 * @returns Promise<T> - A promise that resolves with the deserialized object
 *
 * @example
 * ```typescript
 * // Fetching and deserializing a response
 * const response = await fetch("https://api.example.com/stream");
 * const data = await deserializeResponse<{
 *   status: string;
 *   result: Promise<{ completed: boolean }>;
 *   updates: AsyncIterable<string>;
 * }>(response);
 *
 * console.log(data.status); // "processing"
 * console.log(await data.result); // { completed: true }
 * for await (const update of data.updates) {
 *   console.log(update); // "step 1", "step 2"
 * }
 * ```
 */
export function deserializeResponse(response, 
// deno-lint-ignore no-explicit-any
opts = {}) {
    if (!response.body) {
        throw new Error("Response body is null");
    }
    if (!opts.transformers) {
        opts.transformers = [JSON.parse];
    }
    const reader = response.body.getReader();
    const decoder = new TextDecoder();
    let buffer = "";
    function transform(chunk) {
        const transformed = opts.transformers.reduce((acc, cur) => acc = cur(acc), chunk);
        return transformed;
    }
    /**
     * Generator that reads the response stream and yields parsed JSON objects
     * Handles buffering of partial chunks and NDJSON parsing
     */
    async function* streamChunks() {
        try {
            while (true) {
                const { done, value } = await reader.read();
                if (done)
                    break;
                buffer += decoder.decode(value, { stream: true });
                const lines = buffer.split("\n");
                buffer = lines.pop() || "";
                for (const line of lines) {
                    if (line.trim()) {
                        yield transform(line);
                    }
                }
            }
            const remaining = decoder.decode();
            if (remaining.trim()) {
                console.log("remainig");
                yield transform(remaining);
            }
        }
        finally {
            reader.releaseLock();
        }
    }
    return deserialize(streamChunks());
}
/**
 * Alias for deserializeResponse
 * @template T - The expected type of the deserialized object
 */
export const fromResponse = deserializeResponse;
export default deserializeResponse;