Where did you get this "Java failed" idea? Java is one of the most widely used languages in the whole world...

Java failed as a portable language-agnostic VM for user-facing apps.

You know, the use-case it was originally designed for. (I read the hype for Java 1.0, I was there.)

Nobody at the time could imagine that Java would eventually become the enterprise COBOL replacement.

I'm not so sure it failed. I use IntelliJ IDEA daily, people in my office use WebStorm for Javascript development. There are Swing applications out there that people use, admittedly the ones I've seen are mostly business software. And of course all Android applications are leveraging Java.

It's argued that only IDEs use Java, but Java + Swing strikes me as the most popular cross-platform language and toolkit currently in use.

that's only if you don't consider "web/browser" to be "cross-platform"

We develop on Windows, deploy across OS X, Windows, UNIX, mainframes and embedded devices, without re-compiling.

Looks pretty much living the dream of portable language-agnostic VM for user-facing apps to me.

Java didn't succeed in terms of running code in a web page but it has been wildly successful in regards to "write once, run everywhere". It is widely deployed and has been successful isolating code specific to a particular OS or platform.

While it's clear that Javascript has been successful in the "run code in a web page" sense, it's primary deployment target remains the web browser; even when it's marketed as a cross-platform solution it's often targeting something like Electron.

WebAssembly has its work cut out for it trying to succeed in both of these spaces. I think the project might enhance it's chances for success by remembering Java and its browser plugin rather than pretending they are the first.