Pattern: the synchronous callback -- the callback that is called at the same time [in the same processing cycle] that the function is called.

pattern_synchronousCallback.js

/* 
  the synchronous callback:
  
  create a function that can be called at a later time whenever the 
  higher order function (the function that were passing this function into -- aka: the function doing the calling)
  is ready to call/invoke this function. Read this a few times and it will eventually make sense :)  
*/
   whenDone = function () {
    console.log ("done")
   };
   
   doWork = function(callback) {
     //do some work
     callback(); //the synchronous call - note: in an asynchronous call, this would be called at a later time
   };
   
   //call doWork(whenDone) //output: "done"