check array inside an array length is empty then remove the parent array from the main array

Question

Hi How to check array inside an array length is empty then remove the parent array from the main array ,

think about i have an array

[
    {
        "id": 71,
        "campaignAssets": [
            {
                "id": 128
            }
        ]
    },
    {
        "id": 99,
        "campaignAssets": []
    }
]

from above array id:71 have campaignAssets array which is length is 1 but on the other one "id": 99 dont have the campaignAssets so i have to remove the parent array which means

    {
        "id": 99,
        "campaignAssets": []
    }

so final array should be

[
    {
        "id": 71,
        "campaignAssets": [
            {
                "id": 128
            }
        ]
    }
]

Nina Scholz · Answer 1 · 2016-06-28T11:32:00.770

This proposal features two solutions,

generate a new array and assign it to the original array
delete unwanted items without generating a temporary.

1. With a new array

You could filter it with Array#filter

var data = [{ "id": 71, "campaignAssets": [{ "id": 128 }] }, { "id": 99, "campaignAssets": [] }];

data = data.filter(function (a) { return a.campaignAssets.length; });

console.log(data);

In ES6 it's even shorter

var data = [{ "id": 71, "campaignAssets": [{ "id": 128 }] }, { "id": 99, "campaignAssets": [] }];

data = data.filter(a => a.campaignAssets.length);

console.log(data);

2. Without a new array

For a in situ solution, keeping the array and delete only the elements with zero length, I suggest to use backward iteration and check the length and use Array#splice accordingly.

var data = [{ "id": 71, "campaignAssets": [{ "id": 128 }] }, { "id": 99, "campaignAssets": [] }],
    i = data.length;

while (i--) {
    if (!data[i].campaignAssets.length) {
        data.splice(i, 1);
    }
}

console.log(data);

I'd suggest keeping enforcing the callback on `.filter` of returning a boolean by `return (a.campaignAssets.length > 0)` — Icycool, Jun 28 '16 at 10:04
the callback itself uses a truthy/falsey value. *and constructs a new array of all the values for which callback returns a value that coerces to true.* [source](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter) — Nina Scholz, Jun 28 '16 at 10:08

A.T. · Answer 2 · 2016-06-28T11:27:58.910

0

var data =[
    {
        "id": 71,
        "campaignAssets": [
            {
                "id": 128
            }
        ]
    },
    {
        "id": 99,
        "campaignAssets": []
    }
]
var i = data.length;
while (i--) {
    if(data[i].hasOwnProperty('campaignAssets') && data[i]['campaignAssets'].length==0)
       data.splice(i, 1)
}

// This one is wrong implementation as pointed out, it will not delete element from reducing array..
// data.forEach(function(parent,index){
//  if(parent.hasOwnProperty('campaignAssets') && parent['campaignAssets'].length==0)
//       data.splice(index, 1)
// });

console.log(data);

edited Jun 28 '16 at 11:27

answered Jun 28 '16 at 10:03

A.T.

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Your solution will skip some elements because of not decreasing loop index after splice, refer: http://stackoverflow.com/q/24202962/5039495 – Icycool Jun 28 '16 at 10:06
thanks @Icycool , good catch. I updated my answer please check – A.T. Jun 28 '16 at 11:28

check array inside an array length is empty then remove the parent array from the main array

2 Answers2