In 6/12/17 discussion about JS Map, we noticed that Map snuck into ExEx on 6/7/17 (after code review), and concluded that JS Map is not ready for use in PhET code. It looks like Map is ExEx can be replaced with a string->value hash.
At least on of the Expression Exchange maps is using string keys. It looks like another is using objects, so we will need another solution for that one.
In 6/12/17 discussion about JS Map, we noticed that Map snuck into ExEx on 6/7/17 (after code review), and concluded that JS Map is not ready for use in PhET code. It looks like Map is ExEx can be replaced with a string->value hash.