JavaScript: Converting a flat array into a tree like structure without using `eval`

Question

I have an array like this ["aaa","aaa","bbb","ccc"].

what I need is convert it into a form like this:

{ "aaa" :
  { "aaa" :
    { "bbb" :
      { "ccc" : 1 }
    }
  }
}

I know eval can do the trick, however is there any prettier solution?

Thank you for reading my post.

Possible duplicate of https://stackoverflow.com/questions/695050/add-a-property-to-a-javascript-object-using-a-variable-as-the-name? — T.J. Crowder, Dec 21 '18 at 14:51
@T.J.Crowder maybe I am trapped somehow. In my brain is using pointer which JS doesn't have, or convert it into something like `eval("return ["aaa"]["aaa"]["bbb"]["ccc"]);`. I know this is stupid ... — NotUser9123, Dec 21 '18 at 14:53
@talves I don't think it's a duplicate, I am convert an array into tree, not an object. — NotUser9123, Dec 21 '18 at 15:32

Ori Drori · Accepted Answer · 2018-12-21T14:50:30.730

5

Use Array.reduceRight(). On each iteration return an object, with the previous result as the value of the current property:

const arr = ["aaa","aaa","bbb","ccc"]

const result = arr.reduceRight((r, s) => ({ [s]: r }), 1)

console.log(result)

edited Dec 21 '18 at 14:50

answered Dec 21 '18 at 14:49

Ori Drori

1 Answers1