That conference code demos

01-firstClassCitizen.js shows the concept of JavaScript functions as "first class citizens" in JavaScript. They can be passed around and executed within other functions via callback. Example showing how () will execute a function

02-closure.js shows the concept of closure in JavaScript. Closure is the concept of an inner function in JavaScript having access to the outer function's (or enclosing functions) variables. This is a concept that allows us to keep variables scoped to the appropriate area withing JavaScript