How to loop through multidimensional array and map field to key

Question

I have an object structured like this:

[
  {
    "ID": 34,
    "parent": 0,
    "title": "Level 1 A",
    "children": []
  },
  {
    "ID": 35,
    "parent": 0,
    "title": "Level 1 B",
    "children": [
      {
        "ID": 36,
        "parent": 35,
        "title": "Level 2 A",
        "children": [
          {
            "ID": 37,
            "parent": 36,
            "title": "Level 3 A",
            "children": []
          },
          {
            "ID": 38,
            "parent": 36,
            "title": "Level 3 B",
            "children": []
          }
        ]
      }
    ]
  }
]

and I'm trying to loop through it and make the "title" the key so I end up with this:

[
  {
    "Level 1 A": {
      "ID": 34,
      "parent": 0,
      "title": "Level 1 A",
      "children": []
    }
  },
  {
    "Level 1 B": {
      "ID": 35,
      "parent": 0,
      "title": "Level 1 B",
      "children": [
        {
          "Level 2 A": {
            "ID": 36,
            "parent": 35,
            "title": "Level 2 A",
            "children": [
              {
                "Level 3 A": {
                  "ID": 37,
                  "parent": 36,
                  "title": "Level 3 A",
                  "children": []
                }

              },
              {
                "Level 3 B": {
                  "ID": 38,
                  "parent": 36,
                  "title": "Level 3 B",
                  "children": []
                }
              }
            ]
          }

        }
      ]
    }
  }
]

I tried something like this, but it doesn't go through the children arrays so only the Level 1 elements get updated:

    for (var i = 0, l = response.length; i < l; i++) {
        map[response[i].title] = response[i];
    }

I believe I need to use some recursion, but I'm having trouble figuring out how to get this done with Javascript. Thanks in advance for any suggestions.

Nikhil Aggarwal · Accepted Answer · 2015-07-16 17:04:06Z

1

You need to update your code to following

function updateArray(arr) {
    var updatedResponse = [];
    for (var i = 0, l = arr.length; i < l; i++) {
        var obj = {};
        if(arr[i].children !== undefined) {
            arr[i].children = updateArray(arr[i].children);
        }
        obj[arr[i].title] = arr[i];
        updatedResponse.push(obj);
  }
  return updatedResponse;
}

var updatedArray = updateArray(response);

For reference - http://plnkr.co/edit/bXloL9VHxuxzOlZkHBTe?p=preview

edited Jul 16, 2015 at 17:04

answered Jul 16, 2015 at 16:39

Nikhil Aggarwal

28.5k4 gold badges46 silver badges61 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

MT3 Over a year ago

Thanks @nikhil. I checked the plnkr link and it doesn't seem to add the new key in the children arrays, though, which is what I'm trying to do. Works for 1st level elements.

Nikhil Aggarwal Over a year ago

@MThomas, I missed that part. You need to do it the same way as done for response. Let me update the answer.

Nikhil Aggarwal Over a year ago

@MThomas - I have updated the answer, please review.

Constuntine · Accepted Answer · 2015-07-16 16:38:39Z

0

To loop through multidimensional arrays, you need multiple nested for loops.

for(var i = 0, l = response.length; i < l; i ++){
    for(var j = 0, k = response.length; j < k; j ++){
        //Do some code here
    }
}

A general rule is for every dimension in the array, you need another loop.

answered Jul 16, 2015 at 16:38

Constuntine

5182 silver badges16 bronze badges

Collectives™ on Stack Overflow

How to loop through multidimensional array and map field to key

2 Answers 2

3 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related