Thunks

thunks.js

//synchronous thunk

function add(x,y){
  return x + y;
}

//wrapper to return a value
var thunk = function(){
  return add(10,15);
}

thunk();

//Asynchronous thunks don't take any values but rather a callback

function addAsync(x,y,cb) {
  setTimeout(function(){
    return cb( x + y );
  }, 1000);
}

var thunk = function(cb){
  addAsync(10,15,cb);
}

thunk(function (sum){
  console.log(sum);
});