Skip to content

fix: fall back to fetch when prerender returns 4xx #276

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
Kikobeats merged 1 commit into from
Aug 17, 2026
Merged

fix: fall back to fetch when prerender returns 4xx #276

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 9 additions & 0 deletions src/index.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -185,6 +185,15 @@ const prerender = PCancelable.fn(
)

const payload = await getPayload(url, opts)
// page.content() succeeds on 4xx/5xx challenge pages; only cancel
// fetch when prerender is actually usable, otherwise keep a 2xx/3xx fetch.
if (payload.statusCode >= 400) {
const { isRejected, ...dataProps } = await fetchRes
if (!isRejected && dataProps.statusCode < 400) {
debug('prerender', { url, state: 'fallback', statusCode: payload.statusCode })
return dataProps
}
}
await fetchRes.cancel()
debug('prerender', { url, state: 'success' })
return payload
Expand Down
57 changes: 56 additions & 1 deletion test/mode.js
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
'use strict'

const { getBrowserContext, test } = require('./helpers')
const { getBrowserContext, runServer, test } = require('./helpers')

const getHTML = require('../src')

Expand Down Expand Up @@ -30,6 +30,61 @@ test("`{ prerender: 'auto' }`", async t => {
t.is(stats.mode, 'fetch')
})

test('prerender 4xx falls back to a successful fetch', async t => {
const url = await runServer(t, (_, res) => {
res.setHeader('content-type', 'text/html')
res.end('<!doctype html><title>About Us</title>')
})

const blockedBrowserless = () => ({
evaluate: () => async () => ({
headers: { 'content-type': 'text/html' },
html: '<html><title>ERROR: The request could not be satisfied</title></html>',
mode: 'prerender',
url: String(url),
statusCode: 403,
redirects: []
})
})

const { stats, html, statusCode } = await getHTML(String(url), {
prerender: true,
getBrowserless: blockedBrowserless
})

t.is(stats.mode, 'fetch')
t.is(statusCode, 200)
t.true(html.includes('About Us'))
})

test('prerender 4xx is kept when fetch is also unsuccessful', async t => {
const url = await runServer(t, (_, res) => {
res.statusCode = 403
res.setHeader('content-type', 'text/html')
res.end('<!doctype html><title>blocked</title>')
})

const blockedBrowserless = () => ({
evaluate: () => async () => ({
headers: { 'content-type': 'text/html' },
html: '<html><title>ERROR: The request could not be satisfied</title></html>',
mode: 'prerender',
url: String(url),
statusCode: 403,
redirects: []
})
})

const { stats, html, statusCode } = await getHTML(String(url), {
prerender: true,
getBrowserless: blockedBrowserless
})

t.is(stats.mode, 'prerender')
t.is(statusCode, 403)
t.true(html.includes('The request could not be satisfied'))
})

test.skip('prerender error fallback into fetch mode', async t => {
const url =
'https://www.sportsnet.ca/hockey/nhl/leafs-john-tavares-return-new-york-hope-positive/'
Expand Down