Qt for WebAssembly

Qt for WebAssembly makes it possible to build Qt applications as WebAssembly modules in order to target Web browsers.

Qt for WebAssembly is currently in development. A tech preview release is scheduled for release with Qt 5.11.

This Wiki page is also a work in progress, please see the development tracking bug for more information: https://bugreports.qt.io/browse/QTBUG-63917

Getting the code

qtbase branch: wip/webassembly ( git clone -b wip/webassembly https://code.qt.io/qt/qtbase.git )

qtdeclarative branch: wip/webassembly ( git clone -b wip/webassembly https://code.qt.io/qt/qtdeclarative.git )

Building Qt

Requirements: Emscripten (known-good version: 1.37.33)

Supported host dev platforms: linux, macOS (Windows is not currently supported)

./configure -xplatform emscripten -confirm-license -opensource -developer-build -release -static -no-thread -nomake tests -nomake examples  -no-dbus -no-headersclean -no-feature-networkinterface  -system-libpng -no-ssl -no-warnings-are-errors --release

make

Building and running applications

/path/to/qmake && make

Start a web server (e.g. "python -m SimpleHTTPServer"), open e.g. localhost:8000/appname.html in a web browser. We test on Chrome, Firefox, and Safari (all desktop). Firefox (nightly) currently has the most performant wasm compiler, and is recommended for dev work.

You can also use:

/path/to/emscripten/emrun --browser=firefox appname.html

Note: If you are using Firefox, you can use CTRL+SHIFT+K to open the debug console.

Known issues

It is not currently possible to use Windows as a host platform. You can find a full list of known issues here: https://bugreports.qt.io/browse/QTBUG-63917