emscripten-core / emscripten

Emscripten: An LLVM-to-WebAssembly Compiler

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Re-enable XHR as fallback for fetch on webview #22026

Closed sbc100 closed 4 months ago

sbc100 commented 4 months ago

In #22015 we switched readAsync to be based on fetch rather than XHR. However that broke the assumption in getBinaryenPromise that was assuming readAsync was XHR-based.

This change reinstates the XHR fallback in the case of webviews where loading from file:// URLs is not only possible but (apparently) common.

Sadly we don't have any webview tests so I have no way to actually test this within our current frameworks.

sbc100 commented 4 months ago

Can we instead enable the Fetch polyfill for webview?

Unfortunately we support webview by default in ENVIRONMENT so this would bloat default builds, but perhaps that can be changed first?

The thing is that fetch is supported in webviews, its just the fetch doesn't support file URLs (even in webviews). I don't think it would be good idea idea to clobber the existing webview.

Also use the fetch polyfill would be a bigger bloat that what is this PR proposes I believe.

sbc100 commented 4 months ago

Can we instead enable the Fetch polyfill for webview?

Unfortunately we support webview by default in ENVIRONMENT so this would bloat default builds, but perhaps that can be changed first?

This current change is actually a codesize win even for default ENVIRONMENT that includes webiew:

$ ./emcc ~/test/hello.c -O3 --closure=1 -o new.js
$ wc -c old.js new.js 
 6051 old.js
 6023 new.js

sbc100 commented 4 months ago

For some of our smallest codesize tests this change is actually at 20% saving!

seanmorris commented 4 months ago

We could probably implement WebView tests with NodeGTK & WebKit2 GTK: https://www.npmjs.com/package/node-gtk https://webkitgtk.org/

I used it to implement a browser using Vrzno as a bridge from Js to php-wasm in node: https://github.com/seanmorris/php-gtk

sbc100 commented 4 months ago

We could probably implement WebView tests with NodeGTK & WebKit2 GTK: https://www.npmjs.com/package/node-gtk https://webkitgtk.org/

Thanks! That could be very useful. I think the problem we have is that we really don't know how many users are targetting vebview in this way. Its hard to know if its worth investing a lot of time developing a test harness :(

I used it to implement a browser using Vrzno as a bridge from Js to php-wasm in node: https://github.com/seanmorris/php-gtk

seanmorris commented 4 months ago

We could probably implement WebView tests with NodeGTK & WebKit2 GTK: https://www.npmjs.com/package/node-gtk https://webkitgtk.org/

Thanks! That could be very useful. I think the problem we have is that we really don't know how many users are targetting vebview in this way. Its hard to know if its worth investing a lot of time developing a test harness :(

I used it to implement a browser using Vrzno as a bridge from Js to php-wasm in node: https://github.com/seanmorris/php-gtk

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