Create encapsulated array JS

Question

I have an object like this:

"1": "test1"
"1.1": "test2"
"1.1.1": "test3"
"1.2": "test4"
"2": "test5"

and I would like to create an array like this:

"data": [
  {"data": "test1",
  "children": [
    {"data": "test2",
    "children": [{"data": "test3"}]},
    {"data": "test4"}]},
  {"data": "test5"}
]

I began to loop the list and split the keys with a dot.
I thought maybe I could first build an returnArray[splitedkey[0]][splitedkey[1]] but I dont know how many levels my list has.

Has anyone an idea how to solve this?

Please provide the code you wrote so far - you will have to use a recursion for a reliable way to reach your goal. — Thomas Kekeisen
– Thomas Kekeisen, Commented Oct 2, 2015 at 10:24

Erman Kadir Kahraman · Accepted Answer · 2022-05-30 07:19:24Z

Non-obvious issues that you'll encounter with this:

Iterating through keys in objects may not conform to the order you wrote them. There's a chance an algorithm will encounter 1.1.1 before encountering 1, so an implementation will need to make blank parents { data: null, children [] }
It's clearly a recursive data structure, must be careful that the recursive algorithm terminates properly with duff data

Here's one solution. setVal will recursively crawl to the correct depth specified by accessPath, an array of accessors (e.g. [1, 1, 1]). nestObj reads through obj, extracts keys, maps them to indicies, and appends them into your return value.

var obj = {
  "1": "test1",
  "1.1": "test2",
  "1.1.1": "test3",
  "1.2": "test4",
  "2": "test5"
}

function setVal (array, accessPath, val) {
  if (accessPath.length === 1) {
    if (array[accessPath] === undefined)
      array[accessPath] = { data: val, children: [] };
    else
      array[accessPath].data = val;
  } else {
    // Deals with out-of-order iteration
    if (array[accessPath[0]] === undefined)
      array[accessPath[0]] = { data: null, children: [] };

    setVal(array[accessPath[0]].children, accessPath.slice(1), val);        
  }
}

function nestObj (obj) {
  var ret = [];
  Object.keys(obj).forEach(function (key) {
    var val = obj[key];
    var accessPath = key.split(".").map(function (entry) {
                                      return parseInt(entry, 10);
                                    });
    setVal(ret, accessPath, val);
  });
  return ret;
}

// The format you specified
var answer = { data: nestObj(obj) };

console.log(obj)
console.log(answer)

You don't necessarily need to use parseInt on the access keys. This algorithim would (mostly) work with any arbitrary string key via an associative array.

Erman Kadir Kahraman · Accepted Answer · 2022-05-29 09:33:15Z

0

Try this:

var a = {"1": "test1", "1.1": "test2", "1.1.1": "test3", "1.2": "test4", "2": "test5"};
var b = {data: []};
Object.keys(a).forEach(function (item, index, arr) {
    if (item.indexOf(".") !== -1) {
        console.log(item, a[item]);
        var sp = item.split(".");
        var parent = b.data[sp[0] - 1];
        for (var i = 1; i < sp.length - 1; i++) {
            parent = parent.children[sp[i] - 1];
        }
        parent.children.push({data: a[item], children: []});
    } else {
        b.data.push({data: a[item], children: []});
    }
});
console.log(b);

edited May 29, 2022 at 9:33

Erman Kadir Kahraman

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answered Oct 2, 2015 at 11:08

Sherali Turdiyev

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