Legacy Mono and Emscripten JavaScript APIs not exported to global namespace

Blazor WebAssembly no longer exports legacy Mono and Emscripten APIs to the global namespace. These APIs are now accessible through the Blazor.runtime object.

Version introduced

.NET 9 GA

Previous behavior

Legacy Mono APIs (MONO and BINDING) and the Emscripten Module object were exported to the global window object. For example, window.Module.FS returned the Emscripten virtual filesystem.

New behavior

The Emscripten Module object is now exported to the Blazor.runtime object. For example, Blazor.runtime.Module.FS returns the Emscripten virtual filesystem. The legacy Mono API for interop (MONO and BINDING) is removed completely and replaced with JSImport/JSExport.

Type of breaking change

This change can affect source compatibility.

Reason for change

This change was made to avoid polluting the global namespace and keep all the APIs accessible from a single Blazor object.

Recommended action

Instead of accessing Emscripten APIs from the window object, access them from the Blazor.runtime object.

Affected APIs

• window.MONO.*
• window.BINDING.*
• window.Module.*