Add fetch() polyfill over XMLHttpRequest for Playground#1707
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Add fetch() polyfill over XMLHttpRequest for Playground#1707bkaradzic-microsoft wants to merge 1 commit into
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Implements a minimal `fetch(input, init)` polyfill in Apps/Playground that wraps XMLHttpRequest. Provides a Response-like result with `.ok`, `.status`, `.statusText`, `.url`, `.text()`, `.arrayBuffer()`, `.json()`, `.blob()`, and a `headers` stub. Self-detecting: no-op if a global `fetch` already exists; bails if XMLHttpRequest is unavailable. Wired into the Playground SCRIPTS list and loaded by AppContext before `ammo.js` / `babylon.max.js` so playground snippets that use the modern `fetch` API can run on Babylon Native's host environments (Chakra and V8), which do not provide `fetch` by default. Babylon Native's `XMLHttpRequest` only dispatches events through `addEventListener` (no `onload`/`onerror` properties) and fires `loadend` rather than `load`; the polyfill listens on `loadend` and inspects `status` to decide resolve/reject. When `responseType` is `arraybuffer`, BN's `XHR.responseText` is empty, so `.text()` decodes the array buffer directly rather than reading `responseText`.
This was referenced May 18, 2026
ryantrem
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May 18, 2026
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Similar question as the other PR - should we just add a full native fetch polyfill? Maybe we could add it to XMLHttpRequest (@bghgary might say no though 😅), or a new polyfill. It would be good to have this in BN anyway so the BJS codebase can use fetch rather than XMLHttpRequest.
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Adds a JS polyfill for
fetchso playgrounds depending on it stop hittingReferenceError: 'fetch' is not defined.Changes:
Apps/Playground/Scripts/fetch_polyfill.js- fullfetch(input, init)wrappingXMLHttpRequestwithResponse-liketext()/arrayBuffer()/json()/blob(). Self-detecting (no-op if globalfetchalready exists). Tailored to BN's XHR which dispatches only viaaddEventListenerand firesloadend(noload). DecodesArrayBufferfor.text()whenresponseTypeisarraybuffer.Apps/Playground/CMakeLists.txt- addsfetch_polyfill.jsto SCRIPTS list.Apps/Playground/Shared/AppContext.cpp- loadsfetch_polyfill.jsbeforefile_polyfill.js.Note: Polyfill resolves the headline error but re-enables 0 tests. 5 affected playground tests still excluded - they hit secondary blockers (4 MSDF tests need
babylonjs-addons, idx 151 needsearcut). Tracked as follow-ups.Verified: regression sweep clean on idx 0/5/10/47/100/165/200.
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).
Recommended landing order
Tier 1 - parallel-reviewable, no source conflicts:
reasonrewrites (5 entries)reasonrewrites (17 entries)Tier 2 - sequential, each touches
Apps/Playground/CMakeLists.txtSCRIPTS list +Apps/Playground/Shared/AppContext.cppLoadScript order; rebase the next branch after the previous merges:Reference policy reminder
Reference PNGs across all 7 PRs come from Babylon.js; never re-baked by BN. Combined diff: 0 PNGs.