R is higher than javascript? I didn't heard it before.

Very different domains.

Web and app developers code apps connecting net front ends to databases. JS front end and maybe obj-c/swift/c#/python/ruby/perl for the middle tier.

R is domain specific to stats/econometrics/engineering/data analysis. It competes with matlab, c++, maybe fortran and recently python.

Tested

IE9 is not fully supported. And doesn't support IE8 and below.

But It's still wonderful.

That's not necessarily a drawback.