JSFiddle - React, Tailwind, and code Playground

JavaScript

var a = {
  "b" : {
    "c" : 1
  }
}

var n = "b.c".split(".");
var x = a;
for(var i = 0; i < n.length; i++){
    if(i == n.length-1) {
        x[n[i]] = 2
    } else {
         x = x[n[i]];
    }
}

console.log(x);
console.log(a);