Comment by dkulchenko

That's not unique to JS.

  $ irb
  irb(main):001:0> 0.1 + 0.2
  => 0.30000000000000004
  irb(main):002:0>


  $ iex
  Erlang/OTP 22 [erts-10.6.2] [source] [64-bit] [smp:16:16] [ds:16:16:10] [async-threads:1] [hipe]

  Interactive Elixir (1.10.2) - press Ctrl+C to exit (type h() ENTER for help)
  iex(1)> 0.1 + 0.2
  0.30000000000000004
  iex(2)>

  $ python
  Python 2.7.17 (default, Dec  2 2019, 13:23:33)
  [GCC 4.2.1 Compatible Apple LLVM 11.0.0 (clang-1100.0.33.12)] on darwin
  Type "help", "copyright", "credits" or "license" for more information.
  >>> 0.1 + 0.2
  0.30000000000000004
  >>>