deep_key.js

var connection = {
    notes: { fcrds: { fcrdns: "Hello World" } }
};

var thing_we_want = "notes.fcrds.fcrdns";

var thing = connection;
var parts = thing_we_want.split('.');
while(parts.length > 0) {
    thing = thing[parts.shift()];
    if (thing == null) break;
}

if (thing == null) throw "Not found";

console.log("We found: " + thing);