[dragonwriter]

> Don't you think `x["foo"] == 5` but `x.foo == 4` is a hell of a lot confusing ?

No, having used lots of OO languages before JS and its “objects are dictionaries are arrays and member access and string indexing and integer indexing are all equivalent and can be used interchangeably, except you can't use member access where the key isn't a valid identifier” approach, which I find more confusing and error prone (though I’ve since had to use JS enough to be proficient in that, too.)

Indexing an object as an indexable collection and accessing a member (field, property, or method) of the object are fundamentally different things, and having a collection item with a particular string index isn’t the same thing as an object member with a similar identifier name.

This use of objects as also quasi-associative-arrays is so broken that JS’s actual associative-array type (Map) can’t use indexing notation because of it, and has to use .get() and .set() instead, unlike the associative array types of most other dynamic languages (and several statically-typed OO languages).

The JS way is less bad as a type-specific behavior (e.g., Ruby ActiveSupport’s HashWithIndifferentAccess), though.