How do I write a function that returns an array containing object keys in Javascript? [duplicate]

Question

var person = {
  firstName: 'Halle',
  lastName: 'Berry',
};

function names(object){
  var arr= [];
  for (var key in object) {
    arr.push(key);
    console.log(arr)
  }
}

names(person);

This is what i have so far. I am trying to return an array containing the object person keys.

Where is function what() {} declared? What is the program currently doing, and how is it different from what you expect it to do? — stealththeninja
– stealththeninja, Commented Nov 5, 2017 at 1:02
Welcome to Stack Overflow. Please take the tour and read How to Ask. — astidham2003
– astidham2003, Commented Nov 5, 2017 at 1:02
Can you tell us which language this is (ideally by editing your question and adding the correct tag)? — Bernhard Barker
– Bernhard Barker, Commented Nov 5, 2017 at 1:12
Sorry I meant to put names when i called the function. I edited it. — Taylor
– Taylor, Commented Nov 5, 2017 at 1:29

stealththeninja · Accepted Answer · 2017-11-05 02:00:08Z

0

Object#keys makes this simple:

var arr = ['a', 'b', 'c'];
console.log(Object.keys(arr)); // console: ['0', '1', '2']

Edit: By clarifying the question (thank you!) and comments received, the implementation was close: it was missing a return statement. Including hasOwnProperty is a good practice to check whether keys belong to the object (true) or are inherited (false).

function names(object){
  var arr= [];
  for (var key in object) {
    if (object.hasOwnProperty(key)) {
      arr.push(key);
    }
  }
  return arr; // this was missing
}

edited Nov 5, 2017 at 2:00

answered Nov 5, 2017 at 1:04

stealththeninja

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