Javascript counting the objects in an array

Question

just looking for a little help. I think I've overcomplicated this. Basically I'm trying to just count the objects in this array filled with different data types. I tried just to separate the objects and count them, but obviously I'm now getting both arrays and objects and counting them. The below outputs 4 when it should be 3.

Any help appreciated, still new to coding.

function countTheObjects(arr) {

let objects = [];
for (let i = 0; i < arr.length; i++) {
  if (typeof arr[i] === 'object')
    objects.push(arr[i]);
}
  return objects.length;
}

console.log((countTheObjects([1, [], 3, 4, 5, {}, {}, {}, 'foo'])))

You can identify whether an object is also an array with Array.isArray. But what will you do with sets, maps, regexes, dates, ...etc, will they count as objects or not? — trincot
– trincot, Commented Aug 29, 2022 at 13:12
Arrays are Objects which is why you’re getting the answer you are. As others have mentioned, use Array.isArray() to test for “array-ness”. — Rob Raisch
– Rob Raisch, Commented Aug 29, 2022 at 13:18

HiddenOne1254 · Accepted Answer · 2022-08-29 13:29:26Z

1

function countTheObjects(arr) {
let objects = [];
for (let i = 0; i < arr.length; i++) {
  if (!Array.isArray(arr[i]) && typeof arr[i] === 'object' &&  arr[i] !== null )
    objects.push(arr[i]);
}
console.log(objects)
  return objects.length;
}

console.log((countTheObjects([1, [], 3, 4, 5, {}, {}, {}, 'foo'])))

edited Aug 29, 2022 at 13:29

answered Aug 29, 2022 at 13:21

HiddenOne1254

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Comments

WillD · Accepted Answer · 2022-08-29 13:29:27Z

1

You can use Array.filter() and Array.isArray() to do this.

Array.filter() will look at each item in the array and keep if it the return value of a callback function is true.

function countTheObjects(arr) {
  return arr.filter((item) => item && typeof item === "object" && !Array.isArray(item)).length;
}

console.log(countTheObjects([1, [], null, '', undefined, 3, 4, 5, {}, {}, {}, 'foo']));

edited Aug 29, 2022 at 13:29

answered Aug 29, 2022 at 13:13

WillD

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8 Comments

ah1917 Over a year ago

Thanks for the response, but it seems to return undefined?

epascarello Over a year ago

@ah1917 than you did something different than what the answer shows.

WillD Over a year ago

That's strange, when I run this in the stack overflow code snippet with "Run Code Snippet" button it returns "3"

epascarello Over a year ago

@WillD I would add (item) => item && typeof item ...

ah1917 Over a year ago

Yeah it runs fine for me on here, but I've tried on two separate consoles now and still receive undefined?

|

Radu Diță · Accepted Answer · 2022-08-29 13:17:22Z

0

You can filter the array based on typeof and also check for array and null.

const countIt = (arr) => arr.filter(item => typeof item === "object" && item !== null && Array.isArray(item) === false).length

answered Aug 29, 2022 at 13:17

Radu Diță

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