Convert array into nested object

Question

Let's say I have the following array: ['product' , 'model', 'version']

And I would like to have an object such as:

{
 product: { 
 model: { 
 version: { 
 }
 }
 }
}

However, that array is dynamic so it could have 2, 3 or fewer more items. How can this be achieved in the most efficient way?

Thanks

• deceze: Do you need to create just exactly this empty object? Or do you need to merge those keys into an existing objects also containing other keys?
• gugateider: It can be anything in the value for now as I got access to the data I need to add to this object, but it needs to be within this structure. Tks

Answer 1

Just turn it inside out and successively wrap an inner object into an outer object:

const keys = ['product', 'model', 'version'];
const result = keys.reverse().reduce((res, key) => ({[key]: res}), {});
// innermost value to start with ^^
console.log(result);

• Cody Geisler: {[key]: res} --- has this always been a thing? [key]:value ?
• deceze: Not always. Computed keys exist since ES2016 or so.
• Charles Wood: Bear in mind that keys.reverse will mutate the original array. Using keys.reduceRight (as suggested below) may be preferable.
• devaent: If you want the final "leaf" of your object tree to contain a value other than an empty object, you can use a ternary keys.reduceRight((res, key, i) => (i === keys.length - 1 ? {[key]: myValue} : {[key]: res}) , {});

Answer 2

You can also do it with Array.prototype.reduceRight:

const result = ['product','model','version'].reduceRight((all, item) => ({[item]: all}), {});
console.log(result);

Answer 3

If I understood request correctly, this code might do what you need:

function convert(namesArray) {
 let result = {};
 let nestedObj = result;
 namesArray.forEach(name => {
 nestedObj[name] = {};
 nestedObj = nestedObj[name];
 });
 return result;
}
console.log(convert(['a', 'b', 'c']));

• gugateider: Worked as expected !! Thanks for your help!!

Answer 4

function convert(namesArray, val) {
 let result = {};
 let nestedObj = result;
 namesArray.forEach((name, index) => {
 nestedObj[name] = index === namesArray.length - 1 ? val : {};
 
 nestedObj = nestedObj[name];
 });
 return result;
}
console.log(convert(["a", "b", "c"], 3));