Showcase examples not loading due to CORS rejection

[vietjtnguyen]

Here's a console dump from Firefox Quantum 57.0.3 (64-bit) on macOS 10.12.6 (16G1036):

loading pref showConsoleLogs before prefs were initialised, you will not get the correct result
content-script.bundle.js:333:7
failed to asynchronously prepare wasm: TypeError: NetworkError when attempting to fetch resource.
EmscriptenApplication.js:15:9
TypeError: NetworkError when attempting to fetch resource.
EmscriptenApplication.js:19:9
TypeError: NetworkError when attempting to fetch resource.
EmscriptenApplication.js:15:9
Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at http://static.magnum.graphics/showcase/textured-triangle/magnum-textured-triangle.wasm. (Reason: CORS header ‘Access-Control-Allow-Origin’ missing).
uncaught exception: abort({}) at jsStackTrace@http://static.magnum.graphics/showcase/textured-triangle/magnum-textured-triangle.js:1:17995
stackTrace@http://static.magnum.graphics/showcase/textured-triangle/magnum-textured-triangle.js:1:18166
abort@http://static.magnum.graphics/showcase/textured-triangle/magnum-textured-triangle.js:1:232082
doNativeWasm/<@http://static.magnum.graphics/showcase/textured-triangle/magnum-textured-triangle.js:1:29561

If this abort() is unexpected, build with -s ASSERTIONS=1 which can give more information.

In particular: Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at http://static.magnum.graphics/showcase/textured-triangle/magnum-textured-triangle.wasm. (Reason: CORS header ‘Access-Control-Allow-Origin’ missing).

Similar thing in Chrome 63.0.3239.84 (Official Build) (64-bit):

Failed to load http://static.magnum.graphics/showcase/textured-triangle/magnum-textured-triangle.wasm: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://magnum.graphics' is therefore not allowed access. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.
EmscriptenApplication.js:15 failed to asynchronously prepare wasm: TypeError: Failed to fetch
printErr @ EmscriptenApplication.js:15
(anonymous) @ magnum-textured-triangle.js:1
Promise rejected (async)
doNativeWasm @ magnum-textured-triangle.js:1
Module.asm @ magnum-textured-triangle.js:1
(anonymous) @ magnum-textured-triangle.js:1
EmscriptenApplication.js:19 TypeError: Failed to fetch
EmscriptenApplication.js:15 TypeError: Failed to fetch
printErr @ EmscriptenApplication.js:15
abort @ magnum-textured-triangle.js:1
(anonymous) @ magnum-textured-triangle.js:1
Promise rejected (async)
doNativeWasm @ magnum-textured-triangle.js:1
Module.asm @ magnum-textured-triangle.js:1
(anonymous) @ magnum-textured-triangle.js:1
magnum.graphics/:1 Uncaught (in promise) abort({}) at Error
    at jsStackTrace (http://static.magnum.graphics/showcase/textured-triangle/magnum-textured-triangle.js:1:17995)
    at stackTrace (http://static.magnum.graphics/showcase/textured-triangle/magnum-textured-triangle.js:1:18166)
    at abort (http://static.magnum.graphics/showcase/textured-triangle/magnum-textured-triangle.js:1:232082)
    at http://static.magnum.graphics/showcase/textured-triangle/magnum-textured-triangle.js:1:29561
    at <anonymous>
If this abort() is unexpected, build with -s ASSERTIONS=1 which can give more information.

Relevant part: Failed to load http://static.magnum.graphics/showcase/textured-triangle/magnum-textured-triangle.wasm: No 'Access-Control-Allow-Origin' header is present on the requested resource.

Using the "Allow-Control-Allow-Origin: *" Chrome Extension resolves this on Chrome.