Elm has interop, it's called ports. What the poster is referring to is that Elm 0.18 had an unsupported, undocumented way of calling javascript code directly.

Elm has interop, it's called ports. What the poster is referring to is that Elm 0.18 had an unsupported, undocumented way of calling javascript code directly. This was inherently unsafe (Javascript can throw exceptions and Elm doesn't support exceptions, let alone catching them) and people were abusing it, so it was removed from the language in 0.19.