Wasm 3.0, with its GC and exception support, contains everything you need. The rest is up to the source language to deal with. For example, in Scala.js [1], which is mentioned in the article, you can use the full extent of JavaScript interop to call DOM methods right from inside your Scala code. The compiler does the rest, transparently bridging what needs to be.

[1] https://www.scala-js.org/doc/project/webassembly.html