true == 1 → true

true == "1" → true

false == 0 → true

false == "0" → true

false == undefined → false

false == null → false

null == undefined → true

"\t\r\n" == 0 → true

"\t\r\n 16 \t\r\n" == 16 → true

"\t\r\n 16 \t\r\n" == "16" → false

var a = "foobar"

var b = typeof a → 'string'

var c = a instanceof String → false

[1] https://whydoesitsuck.com/why-does-javascript-suck/

I think this is something you need to blame UNIX for. Or who knows, maybe something made even earlier.

That said, there is a logic behind that. Days we usually represent with numbers. Months we often represent with names. So the month numbers are returned as an index of a sequence of names. (Not saying I like this logic, but it sort of makes sense.)

Continuing forward with bad designs doesn't absolve you from them, though. Plenty of languages avoid this--look at how .NET handles dates and times, it has no real relation to the underlying OS on either Windows or *nix.

  myArray.forEach( (item) => {
    // process item
  });

  for (item in myObject) {
    // process item 
  }