How to create a nested object given an array of keys

Question

Given is an array like this:

var level = ["a", "b", "x"]; 

The output should be:

{     "a": {         "b": {             "x": {             }         }     } } 

I tried this:

var level = ["a", "b", "x"]; var o = {}; for (var c = 0, len = level.length; c < len; c +=1 ) {      var part = level[c];      o[part] = {}; // how to remember the last part? } 

How can I remember the last part and add the next level?

Answer 1

You can use reduceRight method by passing an arrow function as argument.

var level = ["a", "b", "x"];  let result = level.reduceRight((obj, elem) => ({[elem]: obj}), {});  console.log(result);

Answer 2

Simplest tweak would be to reassign o on each iteration:

var level = ["a", "b", "x"];  var o = {};  var initialO = o;  for (var c = 0, len = level.length; c < len; c +=1 ) {     var part = level[c];    o[part] = {};    o = o[part];  }  console.log(initialO);

This might be a clearer way of doing it, though:

const level = ["a", "b", "x"];  const result = {};  level.reduce((accum, key) => {    accum[key] = {};    return accum[key];  }, result);  console.log(result);