How to create a complex/nested js object dynamically?

Question

I have the following data.

var data = "a.b.c.d"; //Just an example but can be more deep.

A nested structure as a string to create a.b.c.n

Now i want to create a js object from this data like this..

{
  "a":{
     "b":{
        "c":{
            and so on till the given depth.  
          }
       }
  }

}

What i have tried

function createHierarchy( obj, group, i){

    if(i === group.length){
        return obj;
    }
    else{
        if(obj[group[i]] === undefined)
        {
            obj[group[i]] = new Object();

        }

        createHierarchy(obj[group[i]], group, ++i); 
    }
}

Problem

This function is returning me undefined as i am sending the newly created subobject in every recursive call and since the newly created object is {} , hence the final result is undefined.

Update

I want to create the object only if it does not exist.For eg : if d already exists ill insert a value into it. else ill create it.

So this is what i added to @Tholle's answer.

if(temp[array[i]] === undefined)
            temp = temp[array[i]] = {};
        else
            temp = temp[array[i]][name] = value;

So kindly suggest a way out.

@StoyanDekov I dont think that would help, as the text that parse function needs has to be a an js object(of type string) ...Right ? And i don't have that — cafebabe1991
– cafebabe1991, Commented Jul 13, 2015 at 18:47
Can you provide an example of your nested structure, or is it simply a string such as 'a.b.c.n'? — Rick Hitchcock
– Rick Hitchcock, Commented Jul 13, 2015 at 18:52
How is the data you're getting structured? If you provide an example we might be able to give better suggestions. — Vale
– Vale, Commented Jul 13, 2015 at 18:53

Tholle · Accepted Answer · 2015-07-13 19:07:11Z

7

var data = "a.b.c.n";
var array = data.split(".");

var result = {};
var temp = result;
for(var i = 0; i < array.length; i++) {
    temp = temp[array[i]] = {};
}

console.log(result);

edited Jul 13, 2015 at 19:07

answered Jul 13, 2015 at 19:00

Tholle

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5 Comments

cafebabe1991 Over a year ago

temp and result point to same location and hence every change in temp is reflected in result ? Is that it ?

Tholle Over a year ago

Right on the money. And for every iteration in the loop, the temp variable references one level deeper, and the result variable is just a reference to the entire object.

cafebabe1991 Over a year ago

One more thing , i would like to create an object only if it does not exist.

Tholle Over a year ago

@cafebabe1991 Consider making another question, since this one is answered.

cafebabe1991 Over a year ago

I think its just an enhancement so i did not add a new question....But i did it , ill update the post. Thanks .

mz3 · Accepted Answer · 2015-07-13 19:05:30Z

2

function BuildObj(string) {
  var obj = {};
  var params = string.split(".");
  for(var i=params.length-1;i>=0;i--) {
    last = obj;
    obj = {};
    obj[params[i]] = last;
  }
  return obj;
}

So,

buildObj("a.b.c.d");

Gives:

{
  "a": {
    "b": {
      "c": {
        "d": {}
      }
    }
 }

answered Jul 13, 2015 at 19:05

mz3

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Comments

Shiva Charan · Accepted Answer · 2017-05-04 15:58:11Z

1

var data = "a.b.c.n";
var array = data.split(".");

var last = {};
var temp = {};
for (var i = array.length - 1; i >= 0; i--) {
  temp = {};
  temp[array[i]] = last;
  last = temp;
}

console.log(last);

https://jsfiddle.net/qo21eh84/2/

answered May 4, 2017 at 15:58

Shiva Charan

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