JSFiddle - React, Tailwind, and code Playground

JavaScript

var foo = 'a.b.c';
var bar = {
        a: {
            b: {
               c: null
            }
         }
    }

function setVal(obj, accessors, val) {
    var parts = accessors.split('.');

    for(var i = 0; i < parts.length-1; i++) {
        obj = obj[parts[i]] 
    }
    
    obj[parts[parts.length-1]] = val;
}

function getVal(obj, accessors) {
    var parts = accessors.split('.');

    for(var i = 0; i < parts.length; i++) {
        obj = obj[parts[i]] 
    }
    
    return obj;
}

setVal(bar, foo, 'Hello World');

alert(getVal(bar, foo));