Iterator and Generator in Js

 Difference between for-in and for-of

let object1 = {
      

let arr = [1,2,3,4];

for (let key in arr) {

//key = 0,1,2,3

}

for (let key in object1) {

//key = 0,1,2,3

}

For-in can do both array and object

For-of can do object, it does only array

What is iterable?

enumerable as false makes non iterable

getOwnPropertyD

Symbol is datatype added in typescript , if we add a 

Generator

yeild

To make an object, we can use the define property method itself to make enumerable as true instead of going for generator/ extending object with symbol.iterator right?
What is advantage and when we go for generator/symbol iterator?