qt webassembly

https://doc.qt.io/qt-6/wasm.html#install-emscripten

The Emscripten versions are:

• Qt 6.2: 2.0.14
• Qt 6.3: 3.0.0
• Qt 6.4: 3.1.14
• Qt 6.5: 3.1.25
• Qt 6.6: 3.1.37
• Qt 6.7: 3.1.50
• Qt 6.8: 3.1.56

Use emsdk to install specific Emscripten versions. For example, to install it for Qt 6.8 enter:

• ./emsdk install 3.1.56
• ./emsdk activate 3.1.56