Sort objects in array by multiple property (possibility does not exist)

Question

I am trying to sort this array:

[
  {
    "id": 877234004,
    "name": "app.js",
    "type": "FILE",
    "parentId": 877234003
  },
  {
    "id": 877234010,
    "name": "project",
    "type": "DIRECTORY"
  },
  {
    "id": 877234002,
    "name": "src",
    "type": "DIRECTORY",
    "parentId": 877234010
  },
  {
    "id": 877234003,
    "name": "app",
    "type": "DIRECTORY",
    "parentId": 877234002
  }
]

As you can see, there are object who doesn't have parentId. I need to keep this one on the top and the rest will be sorted by id.

Here's my code:

input.sort(function (a, b) {
    if (typeof a.parentId === 'undefined')) 
      return -1;
    else
      return a.id - b.id;
  });

It doesn't work though. Is it possible to do this?

Expected result:

[
  {
    "id": 877234010,
    "name": "project",
    "type": "DIRECTORY"
  },
  {
    "id": 877234002,
    "name": "src",
    "type": "DIRECTORY",
    "parentId": 877234010
  },
  {
    "id": 877234003,
    "name": "app",
    "type": "DIRECTORY",
    "parentId": 877234002
  },
  {
    "id": 877234004,
    "name": "app.js",
    "type": "FILE",
    "parentId": 877234003
  }
]

Thanks in advance

if sorting in descending order then in expected result parentId 877234003 will come first then parentId 877234003. pls edit your question. — Shiv Kumar Baghel
– Shiv Kumar Baghel, Commented Jan 2, 2019 at 5:32

Shiv Kumar Baghel · Accepted Answer · 2019-01-02 05:33:32Z

2

i would suggest to use lodash js library

var arr = [
  {
    "id": 877234004,
    "name": "app.js",
    "type": "FILE",
    "parentId": 877234003
  },
  {
    "id": 877234010,
    "name": "project",
    "type": "DIRECTORY"
  },
  {
    "id": 877234002,
    "name": "src",
    "type": "DIRECTORY",
    "parentId": 877234010
  },
  {
    "id": 877234003,
    "name": "app",
    "type": "DIRECTORY",
    "parentId": 877234002
  }
];

var sortedArr = _.orderBy(arr, 'parentId', 'desc');

console.log(sortedArr);

<script src="https://cdn.jsdelivr.net/npm/[email protected]/lodash.min.js"></script>

edited Jan 2, 2019 at 5:33

answered Jan 2, 2019 at 5:28

Shiv Kumar Baghel

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Comments

Bibberty · Accepted Answer · 2019-01-02 05:32:12Z

1

Need to test A and B and invert. if A is missing the prop use -1 if B use +1

let arr = [{
    "id": 877234004,
    "name": "app.js",
    "type": "FILE",
    "parentId": 877234003
  },
  {
    "id": 877234010,
    "name": "project",
    "type": "DIRECTORY"
  },
  {
    "id": 877234002,
    "name": "src",
    "type": "DIRECTORY",
    "parentId": 877234010
  },
  {
    "id": 877234003,
    "name": "app",
    "type": "DIRECTORY",
    "parentId": 877234002
  }
];

const sortPredicate = (a,b) => {
  if (a.hasOwnProperty('parentId') === false) {
    return -1;
  } else if(b.hasOwnProperty('parentId') === false) {
    return 1;
  } else {
    return a.id - b.id;
  }
};


console.log(arr.sort(sortPredicate));

answered Jan 2, 2019 at 5:32

Bibberty

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1 Comment

CertainPerformance Over a year ago

An possible optimization would be to return the difference between each hasOwnProperty check.

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