Fix WASM factory blob URL loading (#1527, #1532)#1558
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- Add canUseBlobURLs() to detect restricted environments (Service Workers, extensions, multi-threading)
- Add env.useWasmBlobURL setting ('auto' | true | false) to control blob URL usage
- Skip Cache API operations when blob URLs are disabled (HTTP cache fallback)
- Fix import.meta.url references in blob URL code for correct path resolution
… and the factory)
This will be useful in other places too, I'm sure
xenova
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Mar 5, 2026
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xenova
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Very nice PR! 🙏
I just made some minor updates: moving env detection to env.js and simplifying loadWasmFactory. also updated some comments.
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Problem
Two related bugs in
loadWasmFactory(introduced in v4.0.0-next.3):loadWasmFactory#1532: Theimport.meta.urlstring replacement was broken —new URL(fileName, import.meta.url)inside the blob URL factory resolved againstblob:...instead of the original CDN URL, producing malformed Worker URLs.wasmPathscaused a CORS error when constructing Workers from a different origin (e.g.localhostdev server).Root cause
The factory
.mjsfile was cached and re-executed as a blob URL, butimport.meta.urlinside it becameblob:.... The attempted fix (string-replacingimport.meta.url) was fragile and broke edgecases.Fix
Relies on onnxruntime PR #27411 (merged Feb 26 2026): when
wasmBinaryis pre-set in the ORT config, ORT setslocateFile = (f) => f, bypassing thenew URL(fileName, import.meta.url)call entirely.Changes:
import.meta.urlstring replacements fromloadWasmFactory.wasmbinary and setONNX_ENV.wasm.wasmBinarybefore the factory executes; the.wasmand.mjsfetches run in parallel, with a revert guard: ifwasmBinaryfails,wasmPaths.mjsis reverted so ORT never sees a blob URL without a corresponding binarycanUseBlobURLs()exclude service workers and Chrome extensions from using the blob "hack"useWasmCachenow controls both.wasmbinary caching and.mjsfactory blob URL caching (they are coupled: a blob URL factory is only safe whenwasmBinaryis set)globalThis.process?.versions?.node → falsein the factory blob to prevent Deno's web runtime from entering the Node.js branch; throw a clear error ifuseWasmCache=falseis set in Deno