Add DOM globals polyfill + native AbortController for Playground by bkaradzic-microsoft · Pull Request #1708 · BabylonJS/BabylonNative

bkaradzic-microsoft · 2026-05-18T16:35:40Z

Wires up native AbortController and adds JS polyfills for TextEncoder + PointerEvent so playgrounds depending on DOM globals stop ReferenceError'ing.

Changes:

New Apps/Playground/Scripts/dom_polyfill.js - self-detecting TextEncoder + PointerEvent polyfills.
Apps/Playground/Shared/AppContext.cpp - calls Babylon::Polyfills::AbortController::Initialize(env); loads dom_polyfill.js after file_polyfill.js.
Apps/Playground/CMakeLists.txt - adds dom_polyfill.js to SCRIPTS list; links AbortController plugin.
Apps/Playground/Android/BabylonNative/CMakeLists.txt - adds PRIVATE AbortController to BabylonNativeJNI link list (without this, Android builds fail with missing header - verified via CI).
Apps/Playground/Scripts/validation_native.js - extends document shim with createEvent + dispatchEvent.
Apps/Playground/Scripts/config.json - re-enables 1 test (idx 342).

Note: Polyfill foundation. Remaining affected playground tests need native `dispatchEvent` on canvas / `Image` polyfill / async-module support - out of scope here.

Landing context

This PR is one of 7 splits from the proven CI-green combined preview in draft PR #1702 (see #1702 for the full intended end-state and verified CI run 26044922430).

Note: the original split included an 8th PR (#1709, ES2020+ -> ES2019 syntax-repair polyfill for Chakra). It was closed in favour of investigating @babel/standalone properly (#1711).

Recommended landing order

Tier 1 - parallel-reviewable, no source conflicts:

Fix ExternalTexture_OpenGL throw-stubs to avoid MSVC C4702 under /WX #1703 - ExternalTexture C4702 build fix
Document accurate root cause for post-#1695 pixel-diff fallouts #1704 - config.json reason rewrites (5 entries)
Document accurate root cause for 17 subtle pixel-diff tests #1705 - config.json reason rewrites (17 entries)

Tier 2 - sequential, each touches Apps/Playground/CMakeLists.txt SCRIPTS list + Apps/Playground/Shared/AppContext.cpp LoadScript order; rebase the next branch after the previous merges:

Add File/Blob/FileReader polyfill for Playground (re-enables 19 GLTF tests) #1706 - File/Blob/FileReader polyfill (largest test impact: 19 re-enables)
Add fetch() polyfill over XMLHttpRequest for Playground #1707 - fetch polyfill
Add DOM globals polyfill + native AbortController for Playground #1708 - DOM globals + native AbortController + Android CMake link
Add cubemap auto-expand polyfill for Playground (re-enables 7 PBR tests) #1710 - Cubemap auto-expand polyfill (loaded after babylon.max.js)

Reference policy reminder

Reference PNGs across all 7 PRs come from Babylon.js; never re-baked by BN. Combined diff: 0 PNGs.

…nt.createEvent) Playground tests that use modern browser APIs hit ReferenceErrors on the Chakra-based BN runtime because TextEncoder and PointerEvent are not part of older Chakra's built-ins. Several serializer tests also exercise document.createEvent + element.dispatchEvent shapes that the existing minimal document polyfill in validation_native.js did not cover. - Apps/Playground/Scripts/dom_polyfill.js: new self-detecting JS polyfills for TextEncoder (UTF-8 encode + encodeInto) and PointerEvent (constructor with the MouseEvent + PointerEvent surface). - Apps/Playground/Shared/AppContext.cpp + CMakeLists.txt: wire in the native AbortController polyfill from JsRuntimeHost and load dom_polyfill.js before ammo.js. - Apps/Playground/Scripts/validation_native.js: extend the existing document shim with createEvent, dispatchEvent, addEventListener and a generic-element fallback for createElement so click-event-based serializer tests can run. - Apps/Playground/Scripts/config.json: re-enable "Serialize scene without materials" (idx 342), which now validates with 248 px diff. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

AppContext.cpp includes <Babylon/Polyfills/AbortController.h> and calls Babylon::Polyfills::AbortController::Initialize(env), but the Android- specific CMakeLists at Apps/Playground/Android/BabylonNative did not add AbortController to BabylonNativeJNI's PRIVATE link libraries. The header is published only by the AbortController target, so Android CI failed with 'fatal error: Babylon/Polyfills/AbortController.h file not found'. Linux/macOS/Windows builds were fine because they use the main Apps/Playground/CMakeLists.txt which already links AbortController. Mirror the change there so Android picks up the include directory. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds missing DOM-like globals to the Playground JS host and wires up native AbortController so DOM-dependent playgrounds/tests stop throwing ReferenceError.

Changes:

Adds a self-detecting TextEncoder + PointerEvent polyfill script and loads it in the Playground startup sequence.
Initializes and links the native AbortController polyfill in Playground (including Android JNI link fix).
Extends the validation runner’s document shim with createEvent/dispatchEvent and re-enables one previously excluded test.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
Apps/Playground/Shared/AppContext.cpp	Initializes native `AbortController` and loads `dom_polyfill.js` during startup.
Apps/Playground/Scripts/validation_native.js	Expands the `document`/element shims to support event creation/dispatch used by tests.
Apps/Playground/Scripts/dom_polyfill.js	New polyfills for `TextEncoder` and `PointerEvent` when absent.
Apps/Playground/Scripts/config.json	Re-enables one previously excluded serialization test.
Apps/Playground/CMakeLists.txt	Packages `dom_polyfill.js` and links `AbortController` into Playground.
Apps/Playground/Android/BabylonNative/CMakeLists.txt	Links `AbortController` into `BabylonNativeJNI` to fix Android builds.

bkaradzic-microsoft · 2026-05-18T17:30:12Z

+            var arr = this.encode(input);
+            var n = Math.min(arr.length, dest.length);
+            for (var i = 0; i < n; i++) dest[i] = arr[i];
+            return { read: String(input).length, written: n };


Addressed in b79d9db. encodeInto now normalizes input (treats undefined as the empty string) before computing both the encoded bytes and read, so the returned read count is consistent with what encode() writes.

bkaradzic-microsoft · 2026-05-18T17:30:13Z

+            init = init || {};
+            this.type = String(type || '');
+            this.bubbles = !!init.bubbles;
+            this.cancelable = init.cancelable !== false;


Addressed in b79d9db. cancelable now defaults to false to match the DOM EventInit spec default; callers that need a cancelable event must pass cancelable: true explicitly.

bkaradzic-microsoft · 2026-05-18T17:30:15Z

+    // Chakra has no `globalThis`; use the Function-constructor trick.
+    var g = (new Function('return this'))();


Addressed in b79d9db. Replaced new Function('return this') with a non-eval resolution chain (globalThis -> self -> window -> global) and kept the Function constructor only as a last-resort fallback for runtimes that ship none of those globals.

- Replace `new Function('return this')` with a non-eval globalThis/self/ window/global resolution chain; keep the Function-constructor trick only as a last-resort fallback for runtimes that ship none of the standard globals. - TextEncoder.prototype.encodeInto: normalize `input` (undefined -> empty string) before computing `read`, so the returned read count stays consistent with the bytes written by `encode()` (previously `String(undefined).length` returned 9 for a zero-byte write). - PointerEvent.cancelable: default to `false` (DOM spec EventInit default) instead of `true`; callers that need a cancelable event must pass `cancelable: true` explicitly. Refs PR BabylonJS#1708. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

ryantrem

I guess this makes the tests work, but if a consumer tried to use the same things in their own app, they wouldn't work. Is that really the state we want to be in, or we want to know what things don't work because they aren't polyfilled? I would have thought we would either document these features don't work because we don't polyfill, or we add native polyfills for them.

bkaradzic-microsoft and others added 2 commits May 15, 2026 21:27

Copilot AI review requested due to automatic review settings May 18, 2026 16:35

Copilot AI reviewed May 18, 2026

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bkaradzic-microsoft requested review from CedricGuillemet, bghgary and ryantrem May 18, 2026 16:42

Copilot started reviewing on behalf of bkaradzic-microsoft May 18, 2026 17:42 View session

ryantrem reviewed May 18, 2026

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Add DOM globals polyfill + native AbortController for Playground#1708

Add DOM globals polyfill + native AbortController for Playground#1708
bkaradzic-microsoft wants to merge 3 commits into
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bkaradzic-microsoft:weekend/tpc-1579-dom-globals

bkaradzic-microsoft commented May 18, 2026 •

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		// Chakra has no `globalThis`; use the Function-constructor trick.
		var g = (new Function('return this'))();

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bkaradzic-microsoft commented May 18, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Note: Polyfill foundation. Remaining affected playground tests need native dispatchEvent on canvas / Image polyfill / async-module support - out of scope here.

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bkaradzic-microsoft commented May 18, 2026 •

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Note: Polyfill foundation. Remaining affected playground tests need native `dispatchEvent` on canvas / `Image` polyfill / async-module support - out of scope here.