Dynamically set property of nested object

This function, using the arguments you specified, should add/update the data in the obj container. Note that you need to keep track of which elements in obj schema are containers and which are values (strings, ints, etc.) otherwise you will start throwing exceptions.

obj = {};  // global object

function set(path, value) {
    var schema = obj;  // a moving reference to internal objects within obj
    var pList = path.split('.');
    var len = pList.length;
    for(var i = 0; i < len-1; i++) {
        var elem = pList[i];
        if( !schema[elem] ) schema[elem] = {}
        schema = schema[elem];
    }

    schema[pList[len-1]] = value;
}

set('mongo.db.user', 'root');

Lodash has a _.set() method.

_.set(obj, 'db.mongodb.user', 'root');
_.set(obj, 'foo.bar', 'baz');