for..in loops

Now, I promised to explain why Python's for..in is different from JavaScript's usage. The difference is that JavaScript's for..in is used to iterate over keys in an object, whereas Python's for..in is used as a loop over a discrete set of entities.

Let's look at an example:

const officers = ['Riker','Data','Worf']

const captain = {
  "name": "Jean-Luc Picard",
  "age": 62,
  "serialNumber": "SP 937-215",
  "command": "NCC 1701-D",
  "seniorStaff": officers
}

let myString = ''

for (let x in captain) {
  myString += captain[x] + ' '
}

What do you think myString now equals? Since the purpose of for..in in JavaScript is to go over each key in the object, it's Jean-Luc Picard 62 SP 937-215 NCC 1701-D Riker,Data,Worf.