chore: remove EnvironmentOptions::experimental_fetch dependency by felixrieseberg · Pull Request #51923 · electron/electron

felixrieseberg · 2026-06-08T20:58:36Z

Description of Change

Node.js removed the experimental_fetch option in nodejs/node#62759 since fetch is now unconditionally enabled. We had been patching the field back in so that node_main.cc could read it and node_bindings.cc could pass --no-experimental-fetch to renderer/worker processes.

Neither is necessary:

In ELECTRON_RUN_AS_NODE mode, fetch is always available, so WASM streaming (which depends on Response) should always be set up.
In renderer/worker processes, kNoBrowserGlobals already causes Node's PrincipalRealm::BootstrapRealm to skip internal/bootstrap/web/exposed-window-or-worker.js, which is where fetch/Request/Response/Headers/FormData are defined. Node's fetch globals were never being installed; Blink's win by default.

This drops the patch and the two call sites that depended on it.

Closes #51912.

Note: I've used Claude to help me with writing and verifying this change. To verify, I've build & confirmed that we're using native code both in main and in a renderer with Node. A unit test seemed inappropriate, but to verify:

Details

$ ELECTRON_RUN_AS_NODE=1 e start -e 'console.log(fetch.toString().slice(0,60)); WebAssembly.compileStreaming(Promise.resolve("x")).catch(e=>console.log(e.constructor.name+":",e.message))'
function fetch(input, init = undefined) { // eslint-disable-
TypeError: The "source" argument must be an instance of Response or an Promise resolving to Response. Received type string ('x')

The TypeError originates from Node's internal/wasm_web_api.js, which only runs when SetWasmStreamingCallback has been installed on the isolate. Without it, V8 would throw WebAssembly streaming APIs are not supported.

Renderer with nodeIntegration ‚ I confirmed Blink's fetch is exposed (not Node's undici), via webContents.executeJavaScript:

const { app, BrowserWindow } = require('electron');
const fs = require('fs');
app.whenReady().then(async () => {
  const w = new BrowserWindow({ show: false, webPreferences: { nodeIntegration: true, contextIsolation: false } });
  await w.loadURL('data:text/html,<html></html>');
  const r = await w.webContents.executeJavaScript(`({
    fetchSrc: fetch.toString(),
    fetchIsNative: fetch.toString().includes('[native code]'),
    ResponseIsNative: Response.toString().includes('[native code]'),
    HeadersIsNative: Headers.toString().includes('[native code]'),
    FormDataIsNative: FormData.toString().includes('[native code]'),
    RequestIsNative: Request.toString().includes('[native code]'),
    hasProcess: typeof process !== 'undefined',
    nodeVer: typeof process !== 'undefined' ? process.versions.node : null,
  })`);
  fs.writeFileSync(process.env.OUT_FILE, JSON.stringify(r, null, 2));
  app.exit(r.fetchIsNative && r.ResponseIsNative ? 0 : 1);
}).catch(e => { fs.writeFileSync(process.env.OUT_FILE, 'ERR: ' + e.stack); app.exit(2); });

{
  "fetchSrc": "function fetch() { [native code] }",
  "fetchIsNative": true,
  "ResponseIsNative": true,
  "HeadersIsNative": true,
  "FormDataIsNative": true,
  "RequestIsNative": true,
  "nodeVer": "24.16.0"
}

All five globals report [native code] (Blink). If Node's bootstrap had installed them, fetch.toString() would show the undici wrapper source instead.

Checklist

I have built and tested this change
I have filled out the PR description
I have reviewed and verified the changes
npm test passes
PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: none

Node.js removed the experimental_fetch option in nodejs/node#62759 since fetch is now unconditionally enabled. We had been patching the field back in so that node_main.cc could read it and node_bindings.cc could pass --no-experimental-fetch to renderer/worker processes. Neither is necessary: - In ELECTRON_RUN_AS_NODE mode, fetch is always available, so WASM streaming (which depends on Response) should always be set up. - In renderer/worker processes, kNoBrowserGlobals already causes Node's PrincipalRealm::BootstrapRealm to skip internal/bootstrap/web/exposed-window-or-worker.js, which is where fetch/Request/Response/Headers/FormData are defined. Node's fetch globals were never being installed; Blink's win by default. Drop the patch and the two call sites that depended on it. Closes electron#51912

electron-issue-triage · 2026-06-08T20:59:04Z

AI PR Detected

Hello @felixrieseberg. Due to the high amount of AI spam PRs we receive, if a PR is detected to be majority AI-generated without disclosure and untested, we will automatically close the PR.

We welcome the use of AI tools, as long as the PR meets our quality standards and has clearly been built and tested. If you believe your PR was closed in error, we welcome you to resubmit. However, please read our CONTRIBUTING.md and AI Tool Policy carefully before reopening. Thanks for your contribution.

felixrieseberg · 2026-06-08T20:59:42Z

Whoeps, I should have not added the AI label 😅

dsanders11

A unit test seemed inappropriate

I think this PR should add test coverage in spec/node-spec.ts for node integration:

A simple check that WASM streaming works with fetch in the renderer
That fetch.toString() is [native code] as expected in the renderer

SetIsolateUpForNode now unconditionally registers Node's WASM streaming callback (nodejs/node#62759 dropped the experimental_fetch gate). With kNoBrowserGlobals the JS half of that callback is never installed, so WebAssembly.compileStreaming/instantiateStreaming would crash on CHECK(\!impl.IsEmpty()) in node_wasm_web_api.cc. Re-register Blink's handler via WasmResponseExtensions::Initialize after CreateEnvironment in renderer and worker so Blink's implementation wins. Also drop the now-redundant blink* global stash/restore: with kNoBrowserGlobals Node neither installs nor deletes fetch/Response/etc, so Blink's bindings are never disturbed and the round-trip through blinkfetch was a no-op. Add a spec asserting fetch/Headers/Request/Response/FormData stringify to [native code] in a nodeIntegration renderer.

felixrieseberg · 2026-06-10T18:37:54Z

Tests added!

This PR now supersedes the Node-patch extension in #51953 by handling the callback restoration in Electron's renderer code instead; #51953 remains the right backportable fix for release branches. WASM streaming regression coverage lives in #51953's chromium-spec.ts test, so this PR only adds the [native code] assertion in node-spec.ts.

The blinkfetch/blinkResponse/‚ stash-and-restore dance in electron_renderer_client.cc, web_worker_observer.cc, lib/node/init.ts and lib/worker/init.ts is removed as dead code: under kNoBrowserGlobals Node neither installs nor deletes those globals, so Blink's bindings are never disturbed.

#51953 should land first

dsanders11

#51953 has landed and this PR needs to fix the merge conflict as a result.

The latest changes here also look to have introduced a failure of the "chromium features web workers Worker with nodeIntegrationInWorker has access to EventSource" test.

felixrieseberg requested a review from a team as a code owner June 8, 2026 20:58

electron-cation Bot added the new-pr 🌱 PR opened recently label Jun 8, 2026

felixrieseberg assigned ckerr Jun 8, 2026

felixrieseberg added ai-pr PR that has been determined to be completely or majority untested and ai generated and removed ai-pr PR that has been determined to be completely or majority untested and ai generated labels Jun 8, 2026

electron-issue-triage Bot closed this Jun 8, 2026

felixrieseberg reopened this Jun 8, 2026

dsanders11 reviewed Jun 9, 2026

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dsanders11 added semver/patch backwards-compatible bug fixes target/43-x-y PR should also be added to the "43-x-y" branch. labels Jun 9, 2026

electron-cation Bot removed the new-pr 🌱 PR opened recently label Jun 9, 2026

deepak1556 mentioned this pull request Jun 10, 2026

fix: only set Node's WASM streaming callback when fetch is enabled #51953

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dsanders11 requested changes Jun 10, 2026

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chore: remove EnvironmentOptions::experimental_fetch dependency#51923

chore: remove EnvironmentOptions::experimental_fetch dependency#51923
felixrieseberg wants to merge 2 commits into
electron:mainfrom
felixrieseberg:felixr/remove-experimental-fetch-option

felixrieseberg commented Jun 8, 2026

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felixrieseberg commented Jun 10, 2026 •

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felixrieseberg commented Jun 8, 2026

Description of Change

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felixrieseberg commented Jun 10, 2026 •

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