How can I check the size of an array containing sub arrays?

Question

I want something along the lines of array1.length from the below array:

var array1 = {
 sub1: [1,2,3],
 sub2: ["K","J","H"],
 sub3: ["Mango","Armada","Leffen","Mew2king"],
 sub4: ['1/8"', '3/16"', '1/4"'],
};

Right now I'm getting the following outputs:

console.log(array1) //Object {sub1: Array[3], sub2: Array[3]...}
console.log(array1.length) //undefined
console.log(array1[1]) //undefined
console.log(array1[1].length //Cannot read property 'length' of undefined

Where am I going wrong?

You're not defining an array but an object. array1.sub1.length will give you a length of one of the arrays — Coss, Oct 24 '16 at 13:01
@gurvinder372 Thanks, that worked for what I wanted. Is it possible to define an array containing sub arrays? — Matthew Sirkin, Oct 24 '16 at 13:06
@MatthewSirkin yes, rather than creating array1 as an object, you can create an actual array and sub-arrays as the array items — gurvinder372, Oct 24 '16 at 13:10

score 1 · Answer 1 · answered Oct 24 '16 at 13:01

1

array1 not is a array, is a object. sub1 and so on are arrays, then you can:

array1.sub1.length; // returns 3

answered Oct 24 '16 at 13:01

BrTkCa

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score 1 · Answer 2 · answered Oct 24 '16 at 13:02

1

You have an Object, not an Array.

You could iterate over the keys and get the length of the arrays inside of the object.

var object = { sub1: [1, 2, 3], sub2: ["K", "J", "H"], sub3: ["Mango", "Armada", "Leffen", "Mew2king"], sub4: ['1/8"', '3/16"', '1/4"'] };
Object.keys(object).forEach(function (key) {
    console.log(object[key].length);
});

answered Oct 24 '16 at 13:02

Nina Scholz

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1

But Object.keys is not supported in IE8 and below, Opera and FF 3.6 and below. – Sankar Oct 24 '16 at 13:06
you could use [`for ... in`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...in) loop with a check for [`hasOwnProperty`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/hasOwnProperty) – Nina Scholz Oct 24 '16 at 13:10

score 0 · Answer 3 · answered Oct 24 '16 at 13:04

Try this...

var array1 = {
  sub1: [1, 2, 3],
  sub2: ["K", "J", "H"],
  sub3: ["Mango", "Armada", "Leffen", "Mew2king"],
  sub4: ['1/8"', '3/16"', '1/4"'],
};

console.log(array1.sub1.length,array1.sub2.length,array1.sub3.length,array1.sub4.length);

score 0 · Answer 4 · answered Oct 24 '16 at 13:10

0

You could always do something like this:

var array1 = [[1,2,3],["K","J","H"],["Mango","Armada","Leffen","Mew2king"],
 ['1/8"', '3/16"', '1/4"']];
var flatArray = [].concat.apply([],array1)

This will flatten the array so you can use length etc.

answered Oct 24 '16 at 13:10

Coss

453
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score 0 · Answer 5 · edited May 23 '17 at 11:54

See Converting JSON Object into Javascript array

var array1 = {
 sub1: [1,2,3],
 sub2: ["K","J","H"],
 sub3: ["Mango","Armada","Leffen","Mew2king"],
 sub4: ['1/8"', '3/16"', '1/4"'],
};
alert("Size : "+Object.keys(array1).map(function(k) { return array1[k] }).length);

OUTPUT

Size : 4

HOW IT WORKS

Converting the keys to an array and then mapping back the values with Array.map Then, can get the length of this array. Gg wp.

NB : You can also create a var at the beginning and then use it to all your process.

score -1 · Answer 6 · answered Oct 24 '16 at 13:04

-1

array1 is a JSON object. So

array1.subArray.length

should work

answered Oct 24 '16 at 13:04

Jimmy Adaro

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Unfortunately, it(`array1`) is an object. – Sankar Oct 24 '16 at 13:09
@SankarRaj Thats what I said. `array1` is an object. Don't understand the down vote. – Jimmy Adaro Oct 24 '16 at 13:17

How can I check the size of an array containing sub arrays?

6 Answers6