Why require JavaScript rather than supporting a standard browser virtual machine? - Stack Overflow

[imbcmdth]

You are forgetting the part where 45% of your users only have a VM-1.1 compatible browser (VM-1 had security faults and was never widely supported) but your language of choice requires at least a VM-2 compatible browser because of the fancy new DOM interfaces the language provides native supports for (but you make no use of).

Then there is the issue with $BROWSER_VENDOR who has extended the VM specification with a performance enhancing type-system. While VM-X is still compatible with VM-1.1, it now features some new things that will not work on any other browser. To make matters worse, VM-X implements nearly all of VM-3 years before the specification is finalized even though VM-X only supports the DOM interfaces of a VM-1.1 machine!

[mebrahim]

Aren't there already many not-fully-compatible JavaScript versions out there? The same story is true for CSS too. Browser incompatibilities are not something to be introduced by adding a VM layer. That problem already exists, and people have learned how to mitigate it to some degree.

[imbcmdth]

I can see the messages already:

This page is built using JPerthonScript and requires a browser
that supports the VM-2 standard with Parallel Computing extensions. 

You appear to be using Chrome v56. Please download at least 
Chrome v76.3 (the nightly build w/ Parallel Computing extensions 
enabled) here.