At this point, folks are seeing how far they can push the Typescript type system because it's capable of expressing so, so much more with its types than is seen typically(including in most other languages).
By almost any reasonable measure it is one of the strongest candidates for “biggest success ever as a programming language”. Sure, you can argue that the reasons for that aren’t mainly language design related, but it is absolutely not anything like a failure.
I don't buy this, considering that wasm still doesn't actually have access to the Web APIs that JavaScript has access to (and relies on JS to even be loaded in the first place).
In my opinion, if that's what counts as being a supported language, then JS was never the only supported language to begin with since you could always compile other languages to run on the web through JavaScript (for example Emscripten with the asm.js target predates WebAssembly). The only thing that wasm currently offers over the previous status quo is that it's faster (for some workloads).
But that’s not the same as “JavaScript is a failure”.