How to access the Symbol(Symbol.toStringTag) property?

Question

I'm looking to read the data from the Symbol(Symbol.toStringTag) field of an object - in this case, it should return "Array Iterator".

This does not work

a.__proto__["Symbol(Symbol.toStringTag)"]

Answer 1

Symbol(Symbol.toStringTag) indicates that the property is a symbol . Symbols are unique values and you can only reference such a property if you already have a reference to the symbol.

Luckily Symbol.toStringTag is a well-known symbol , so you can just reference it:

a[Symbol.toStringTag]

---

Here is an example where you cannot access the property directly:

var obj = (function() {
  // prop is a unique value
  var prop = Symbol();
  return {[prop]: 42};
}());

There is no way to access obj[<the symbol>] directly since we don't have access to prop . You can still iterate over the properties though.