Iterate using Object key and findIndex failed

Question

{
  "June": [
    {
      "id": "59361b2fa413468484fc41d29d5",      
      "is_new": false,
      "name":"John"
      "updated_at": "2017-06-07 10:52:05",
    }
  ]
}

I have above object and within it it has array of object, I tried to check within 'June', is there any is_new, but failed?

const has_any_is_new = Object.keys(arr).map(obj => 
    arr[obj].map(obj2 => obj2.findIndex(o => o.is_new) > -1)
);

Possible duplicate of [Iterate through object properties](https://stackoverflow.com/questions/8312459/iterate-through-object-properties) — Michelangelo, Jun 07 '17 at 11:04
you forgot a comma after the `name` property. And you could remove the comma after `updated_at` as well. — Chris, Jun 07 '17 at 11:06
Instead of using `findIndex(…) > -1`, you should just do `some(…)` — Bergi, Jun 07 '17 at 11:06
What exactly failed? What's the expected result, and what did you get instead? — Bergi, Jun 07 '17 at 11:07

score 0 · Answer 1 · answered Jun 07 '17 at 11:10

If you want to test whether any of the items in the June array has is_new==true, you can use .some:

let months = {
  "June" : [
    {
      "id": "59361b2fa413468484fc41d29d5",      
      "is_new": false,
      "name":"John",
      "updated_at": "2017-06-07 10:52:05",
    },
     {
      "id": "59361b2fa413468484fc41d29d6",      
      "is_new": true,
      "name":"John2",
      "updated_at": "2017-06-07 10:52:05",
    }
  ]
}

const has_any_is_new = Object.keys(months).some( month => 
    months[month].some( obj => obj.is_new )
);

console.log(has_any_is_new)

.map just runs a function against each element in an array.

.some returns true if any of the functions it applies returns true.

some is just return true or false right? the comparison is similar to filter, just that filter return the array, am I right? — Alan Jenshen, Jun 08 '17 at 03:16
Yep that's correct. See [Array.prototype.some](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/some) — Jeremy Thille, Jun 08 '17 at 06:52

score -1 · Answer 2 · answered Jun 07 '17 at 11:11

You have one map too much. arr[obj] already refers to the "June" array of objects, so obj2 has the .is_new property but no map method. Use

const obj = { "June": […] };
const news = Object.keys(obj).map(key => 
    [key, obj[key].some(o => o.is_new)]
); // an array of month-boolean-tuples

or

const has_any_is_new = Object.keys(obj).some(key => 
    obj[key].some(o => o.is_new)
); // a boolean whether any month has a new entry

Iterate using Object key and findIndex failed

2 Answers2