Are all data types in JavaScript enumerable?

Question

I know that object properties has 3 flags and with one of them I can set a certain property non-enumerable. But in all other cases are all types of data enumerable?

Answer 1

• By default all properties created using simple assignment or via a property initializer are enumerable irrespective of data type.

• Properties defined via methods like Object.defineProperty, Object.defineProperties are by default non enumerable.

Ex:

1.Property Initilaizer (by default enumerable):

const obj = { a: 'foo', b: 123, c: {} };

2.Simple assignment (by default enumerable):

obj.a = 'foo'
obj.b = 123
obj.c = {}

3.Object's methods (by default non-enumerable):

obj = {};  
Object.defineProperties(obj, 
    {   a: {   value: 'foo' },
    {   b: {   value: 123 },
    {   c: {   value: {} }
);  

Further reference here.