How do I create a nested object structure from a path (array of keys)?

Question

I am trying to make something that takes arrays of strings, and then builds chains of nested objects that basically store what strings come after what in the input arrays. Initially, these chains had depths of 2, but I need to be able to generate higher-depth chains.

Basically, I need to take an array like this:

["test1", "test2", "test3", "test4"]

and convert it into this:

{
    "test1":
    {
        "test2":
        {
            "test3":
            {
                "test4": {}
            }
        }
    }
}

gyre · Accepted Answer · 2017-03-28 05:09:54Z

6

This looks like a job for Array#reduce:

function objectFromPath (path) {
  var result = {}
  
  path.reduce(function (o, k) {
    return (o[k] = {})
  }, result)
  
  return result
}

var path = ["test1", "test2", "test3", "test4"]

console.log(objectFromPath(path))

.as-console-wrapper { min-height: 100%; }

edited Mar 28, 2017 at 5:09

answered Mar 28, 2017 at 5:07

gyre

16.8k4 gold badges40 silver badges47 bronze badges

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

2 Comments

vol7ron Over a year ago

Don't think he's gonna get any better than this

Travis Over a year ago

Thank you for the answer, and especially for editing the title of my question. Now I actually know what what I was trying to do is called!

CanProgram · Accepted Answer · 2021-03-19 23:27:30Z

I wanted to solve a similar problem, but I wanted to set a value at the end of the path within the resulting object, and I wanted to provide an initial object. I started with gyre's function and added some extra magic to satisfy my use case.

// Creates a nested object from an array representing the path of keys
//
// Takes 2 optional arguments:
//     - a value to set at the end of the path
//     - an initial object
// 
// Ex: let house = objectFromPath(['kitchen', 'fridge'], 'empty', {civic: 123})
//     => house = {civic: 123, kitchen: {fridge: 'empty'}}
const objectFromPath = (path, value = {}, obj = {}) =>
{
    path.reduce((result, key, i, source) =>
        {
            if(i === (source.length - 1))
            {
                return (result[key] = value)
            }
            else
            {
                return (result[key] = {})
            }
        },
        obj
    )
    
    return obj;
}


// Demo: house = {civic: 123, kitchen: {fridge: 'empty'}}
console.log(
  objectFromPath(
    ['kitchen', 'fridge'],
    'empty',
    {civic: 123}
  )
)

Collectives™ on Stack Overflow

How do I create a nested object structure from a path (array of keys)?

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related