Improved JavaScript interoperability in .NET 7 RC 1

Published on Oct 07, 2022

As part of the .NET 7 RC 1 release, we are pleased to announce the introduction of the new wasm-experimental workload and new JavaScript interop features, which enable JavaScript applications running on WebAssembly to invoke .NET code without taking advantage of the Blazor UI component model.

The Mono WASM SDK, Uno.Wasm.Bootstrap library or NativeAOT LLVM library were all available to enable WebAssembly without the need for Blazor up until this release. With .NET 7, the new workload and features of Blazor WebAssembly are the basis for Blazor WebAssembly, but it is also possible to use .NET code within a WebAssembly context without the need for specialised libraries or Blazor, and using only utilities from the .NET framework.

The new JSExport attribute can be used for exposing a JavaScript method to .NET code, allowing .NET code to be used inside JavaScript. As soon as it is applied to a method in .NET, the dotnet.js runtime exposes it through the getAssemblyExports function.

Using the JSImport attribute, you can expose a JavaScript method to .NET through the use of code inside JavaScript, so that JavaScript code can be run inside .NET.