JSFiddle - React, Tailwind, and code Playground

JavaScript

var object = {
    prop1: {
        prop2: {
            foo: 1
        }
    }
};

function get(object, key) {
    var keys = key.split('.');
    for (var i = 0; i < keys.length; i++) {
        if (!object.hasOwnProperty(keys[i])) {
            return null;
        }
        object = object[keys[i]];
    }
    return object;
}

console.log(get(object, 'prop1.prop2'));
console.log(get(object, 'prop1.prop3'));