nestStringProperties.js

function nestStringProperties(obj) {
    if (!obj) {
        return {};
    }
    
    const isPlainObject = obj => !!obj && obj.constructor === {}.constructor;
    
    const getNestedObject = obj => Object.entries(obj).reduce((result, [prop, val]) => {
        prop.split('.').reduce((nestedResult, prop, propIndex, propArray) => {
            const lastProp = propIndex === propArray.length - 1;
            if (lastProp) {
                nestedResult[prop] = isPlainObject(val) ? getNestedObject(val) : val;
            } else {
                nestedResult[prop] = nestedResult[prop] || {};
            }
            return nestedResult[prop];
        }, result);
        return result;
    }, {});
    
    return getNestedObject(obj);
}