How to ready dynamic key value from object in js

Question

const a = {"b":{"c":3}}
const z = "b.c"

I have the above values and now I want to get value 3(a.b.c) from a using the z variable. I have tried the below method but it is not working

a.z
${a.z}
${a[z]}
...etc..

Similar to this as well. https://stackoverflow.com/q/6491463/989920 — evolutionxbox, Feb 16 '22 at 12:28

score 2 · Answer 1 · answered Feb 16 '22 at 12:33

2

You can do something like this

function rGetAttr(obj, dotPath){
  return dotPath.split('.').reduce((o,i)=> o[i], obj)
}

const obj = {a: {b: {c: 123}}}
console.log(rGetAttr(obj, "a.b.c"))

answered Feb 16 '22 at 12:33

anjaneyulubatta505

10,713
1
52
62

A reduce! Nice, this is way cleaner than mine – Dutchman Feb 16 '22 at 12:53
It's good that it doesn't throw if the path doesn't exist. – evolutionxbox Feb 16 '22 at 13:30

score 1 · Answer 2 · answered Feb 16 '22 at 12:31

1

You can do it by using Lodash


const _ = require("lodash");

console.log(_.get(a, z));

answered Feb 16 '22 at 12:31

kiran

444
3
15

score 0 · Answer 3 · answered Feb 16 '22 at 12:51

You could do something like this:

const a = {
  "b": {
    "c": 3
  }
}

const keyName = "b";

// This works to access an objects elements by key name
console.log(a[keyName]);

// If you want to be able to have "b.c" then you need to handle the nesting something like this:
const getValue = (obj, prop) => {
    const parts = prop.split('.');
    let thisObj = obj;
    let part = 0;
    while (thisObj = thisObj?.[parts[part++]]) {
        if (part >= parts.length) break;
    }
    return thisObj;
}


const nestedKeyName = "b.c";
// Usage like this:
console.log(getValue(a, nestedKeyName));

How to ready dynamic key value from object in js

3 Answers3