next/dist/esm/client/components/router-reducer/fetch-server-response.js

The React Framework

"use client";

// @ts-ignore
// eslint-disable-next-line import/no-extraneous-dependencies
// import { createFromReadableStream } from 'react-server-dom-webpack/client'
const { createFromReadableStream } = !!process.env.NEXT_RUNTIME ? require('react-server-dom-webpack/client.edge') : require('react-server-dom-webpack/client');
import { NEXT_ROUTER_PREFETCH_HEADER, NEXT_ROUTER_STATE_TREE_HEADER, NEXT_RSC_UNION_QUERY, NEXT_URL, RSC_HEADER, RSC_CONTENT_TYPE_HEADER, NEXT_HMR_REFRESH_HEADER, NEXT_DID_POSTPONE_HEADER, NEXT_ROUTER_STALE_TIME_HEADER } from '../app-router-headers';
import { callServer } from '../../app-call-server';
import { findSourceMapURL } from '../../app-find-source-map-url';
import { PrefetchKind } from './router-reducer-types';
import { hexHash } from '../../../shared/lib/hash';
import { normalizeFlightData } from '../../flight-data-helpers';
function urlToUrlWithoutFlightMarker(url) {
    const urlWithoutFlightParameters = new URL(url, location.origin);
    urlWithoutFlightParameters.searchParams.delete(NEXT_RSC_UNION_QUERY);
    if (process.env.NODE_ENV === 'production') {
        if (process.env.__NEXT_CONFIG_OUTPUT === 'export' && urlWithoutFlightParameters.pathname.endsWith('.txt')) {
            const { pathname } = urlWithoutFlightParameters;
            const length = pathname.endsWith('/index.txt') ? 10 : 4;
            // Slice off `/index.txt` or `.txt` from the end of the pathname
            urlWithoutFlightParameters.pathname = pathname.slice(0, -length);
        }
    }
    return urlWithoutFlightParameters;
}
function doMpaNavigation(url) {
    return {
        flightData: urlToUrlWithoutFlightMarker(url).toString(),
        canonicalUrl: undefined,
        couldBeIntercepted: false,
        prerendered: false,
        postponed: false,
        staleTime: -1
    };
}
/**
 * Fetch the flight data for the provided url. Takes in the current router state
 * to decide what to render server-side.
 */ export async function fetchServerResponse(url, options) {
    const { flightRouterState, nextUrl, buildId, prefetchKind } = options;
    const headers = {
        // Enable flight response
        [RSC_HEADER]: '1',
        // Provide the current router state
        [NEXT_ROUTER_STATE_TREE_HEADER]: encodeURIComponent(JSON.stringify(flightRouterState))
    };
    /**
   * Three cases:
   * - `prefetchKind` is `undefined`, it means it's a normal navigation, so we want to prefetch the page data fully
   * - `prefetchKind` is `full` - we want to prefetch the whole page so same as above
   * - `prefetchKind` is `auto` - if the page is dynamic, prefetch the page data partially, if static prefetch the page data fully
   */ if (prefetchKind === PrefetchKind.AUTO) {
        headers[NEXT_ROUTER_PREFETCH_HEADER] = '1';
    }
    if (process.env.NODE_ENV === 'development' && options.isHmrRefresh) {
        headers[NEXT_HMR_REFRESH_HEADER] = '1';
    }
    if (nextUrl) {
        headers[NEXT_URL] = nextUrl;
    }
    if (process.env.NEXT_DEPLOYMENT_ID) {
        headers['x-deployment-id'] = process.env.NEXT_DEPLOYMENT_ID;
    }
    const uniqueCacheQuery = hexHash([
        headers[NEXT_ROUTER_PREFETCH_HEADER] || '0',
        headers[NEXT_ROUTER_STATE_TREE_HEADER],
        headers[NEXT_URL]
    ].join(','));
    try {
        var _res_headers_get;
        let fetchUrl = new URL(url);
        if (process.env.NODE_ENV === 'production') {
            if (process.env.__NEXT_CONFIG_OUTPUT === 'export') {
                if (fetchUrl.pathname.endsWith('/')) {
                    fetchUrl.pathname += 'index.txt';
                } else {
                    fetchUrl.pathname += '.txt';
                }
            }
        }
        // Add unique cache query to avoid caching conflicts on CDN which don't respect the Vary header
        fetchUrl.searchParams.set(NEXT_RSC_UNION_QUERY, uniqueCacheQuery);
        // When creating a "temporary" prefetch (the "on-demand" prefetch that gets created on navigation, if one doesn't exist)
        // we send the request with a "high" priority as it's in response to a user interaction that could be blocking a transition.
        // Otherwise, all other prefetches are sent with a "low" priority.
        // We use "auto" for in all other cases to match the existing default, as this function is shared outside of prefetching.
        const fetchPriority = prefetchKind ? prefetchKind === PrefetchKind.TEMPORARY ? 'high' : 'low' : 'auto';
        if (process.env.__NEXT_TEST_MODE) {
            headers['Next-Test-Fetch-Priority'] = fetchPriority;
        }
        const res = await fetch(fetchUrl, {
            // Backwards compat for older browsers. `same-origin` is the default in modern browsers.
            credentials: 'same-origin',
            headers,
            priority: fetchPriority
        });
        const responseUrl = urlToUrlWithoutFlightMarker(res.url);
        const canonicalUrl = res.redirected ? responseUrl : undefined;
        const contentType = res.headers.get('content-type') || '';
        const interception = !!((_res_headers_get = res.headers.get('vary')) == null ? void 0 : _res_headers_get.includes(NEXT_URL));
        const postponed = !!res.headers.get(NEXT_DID_POSTPONE_HEADER);
        const staleTimeHeader = res.headers.get(NEXT_ROUTER_STALE_TIME_HEADER);
        const staleTime = staleTimeHeader !== null ? parseInt(staleTimeHeader, 10) : -1;
        let isFlightResponse = contentType.startsWith(RSC_CONTENT_TYPE_HEADER);
        if (process.env.NODE_ENV === 'production') {
            if (process.env.__NEXT_CONFIG_OUTPUT === 'export') {
                if (!isFlightResponse) {
                    isFlightResponse = contentType.startsWith('text/plain');
                }
            }
        }
        // If fetch returns something different than flight response handle it like a mpa navigation
        // If the fetch was not 200, we also handle it like a mpa navigation
        if (!isFlightResponse || !res.ok || !res.body) {
            // in case the original URL came with a hash, preserve it before redirecting to the new URL
            if (url.hash) {
                responseUrl.hash = url.hash;
            }
            return doMpaNavigation(responseUrl.toString());
        }
        // We may navigate to a page that requires a different Webpack runtime.
        // In prod, every page will have the same Webpack runtime.
        // In dev, the Webpack runtime is minimal for each page.
        // We need to ensure the Webpack runtime is updated before executing client-side JS of the new page.
        if (process.env.NODE_ENV !== 'production' && !process.env.TURBOPACK) {
            await require('../react-dev-overlay/app/hot-reloader-client').waitForWebpackRuntimeHotUpdate();
        }
        // Handle the `fetch` readable stream that can be unwrapped by `React.use`.
        const flightStream = postponed ? createUnclosingPrefetchStream(res.body) : res.body;
        const response = await createFromReadableStream(flightStream, {
            callServer,
            findSourceMapURL
        });
        if (buildId !== response.b) {
            return doMpaNavigation(res.url);
        }
        return {
            flightData: normalizeFlightData(response.f),
            canonicalUrl: canonicalUrl,
            couldBeIntercepted: interception,
            prerendered: response.S,
            postponed,
            staleTime
        };
    } catch (err) {
        console.error("Failed to fetch RSC payload for " + url + ". Falling back to browser navigation.", err);
        // If fetch fails handle it like a mpa navigation
        // TODO-APP: Add a test for the case where a CORS request fails, e.g. external url redirect coming from the response.
        // See https://github.com/vercel/next.js/issues/43605#issuecomment-1451617521 for a reproduction.
        return {
            flightData: url.toString(),
            canonicalUrl: undefined,
            couldBeIntercepted: false,
            prerendered: false,
            postponed: false,
            staleTime: -1
        };
    }
}
function createUnclosingPrefetchStream(originalFlightStream) {
    // When PPR is enabled, prefetch streams may contain references that never
    // resolve, because that's how we encode dynamic data access. In the decoded
    // object returned by the Flight client, these are reified into hanging
    // promises that suspend during render, which is effectively what we want.
    // The UI resolves when it switches to the dynamic data stream
    // (via useDeferredValue(dynamic, static)).
    //
    // However, the Flight implementation currently errors if the server closes
    // the response before all the references are resolved. As a cheat to work
    // around this, we wrap the original stream in a new stream that never closes,
    // and therefore doesn't error.
    const reader = originalFlightStream.getReader();
    return new ReadableStream({
        async pull (controller) {
            while(true){
                const { done, value } = await reader.read();
                if (!done) {
                    // Pass to the target stream and keep consuming the Flight response
                    // from the server.
                    controller.enqueue(value);
                    continue;
                }
                // The server stream has closed. Exit, but intentionally do not close
                // the target stream.
                return;
            }
        }
    });
}

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