JavaScript - retrieve value from nested object, using array of keys

Question

How can I get a value from a nested object, using an array of keys?

// my sample object
var obj = {
    type            : "Purchase",
    category        : "Apartment",
    categoryOptions : {
       apartment : {
           floors    : {
               type        : "number",
               value       : null,
               placeholder : "Total Floors"
           },
       },
    },
}
var keysArray = ["value", "floors", "apartment", "categoryOptions"]

I tried to use array.reduceRight to achieve this but could not make it work.

here is what I've tried :

var roadToValue = keysArray.reduceRight(
    function(previousValue, currentValue){
        return previousValue + "[" + currentValue + "]" ;
    }
);
// above function results in a single string like 
// "categoryOptions[apartment][floors][value]" 
// which off-course can't be used as object key
// and obj[roadToValue] results in 'undefined'

is there any way so I can get the proper key to pass to obj here?

@corn3lius oh its a typo in writing the question. my problem still exist. i will update the question. — Taxellool
– Taxellool, Commented Jun 16, 2017 at 13:44

Christoph · Accepted Answer · 2017-06-16 13:56:29Z

7

You definitely can use reduceRight for this. The problem is that you created a string, however you need to pass your object as initialValue and use the squared bracket notation:

var obj = {"type":"Purchase","category":"Apartment","categoryOptions":{"apartment":{"floors":{"type":"number","value":null,"placeholder":"Total Floors"}}}}
var keysArray = ["value", "floors", "apartment", "categoryOptions"]

var value = keysArray.reduceRight((r, e) => r[e] || r, obj)
console.log(value)

edited Jun 16, 2017 at 13:56

Christoph

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answered Jun 16, 2017 at 13:45

Nenad Vracar

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1 Comment

Christoph Over a year ago

I included an undefined check, now it will return the object where the error occured.

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