Looping through arrays inside an object

Question

In JavaScript, it is possible to loop through an object using the Object.keys method. With this, I can loop the person Object as:

  let person: {

    name:     "John",
    lastName: "Doe",
    age:       31,

  }

  for (let key of Object.keys(person)) {
     console.log(person[key])
  }

Now, how is it possible to do this if the person has arrays as properties?

 person: {

    name:     "John",
    lastName: "Doe",
    age:       31,    

    address: [{
     street:    "A Street Name",
     number:    190,
     apartment: 13
    }]

  }

[Javascript Arrays are also Objects](https://stackoverflow.com/questions/5048371/are-javascript-arrays-primitives-strings-objects) — smac89, Jan 09 '20 at 15:50

score 2 · Answer 1 · answered Jan 09 '20 at 15:51

It's not very clear what your're trying to accomplish, but going off your example, you can iterate prop1, prop2, prop3 values:

let object = {
  array: [{
    prop1: 1,
    prop2: 2,
    prop3: 3
  }]
};

for (key in object.array[0])
  console.log(key, object.array[0][key]);

score 0 · Accepted Answer · answered Jan 09 '20 at 15:53

Try to use Object.entries:

Object.entries(object).forEach(([k, v]) => {
    if (Array.isArray(v)) {
        let keys = Object.keys(...v);
        console.log(keys)
    }
});

An example:

let object = {
    array: [
        {
     prop1: 1,
     prop2: 2,
     prop3: 3
    }]
  }

Object.entries(object).forEach(([k, v]) => {
    if (Array.isArray(v)) {
        let keys = Object.keys(...v);
        console.log(keys)
    }
});

Looping through arrays inside an object

2 Answers2