Syntax of Closures

Question

function makeIncreaseByFunction(increaseByAmount) {
  return function (numberToIncrease) {
    return numberToIncrease + increaseByAmount;
  };
}

makeIncreaseByFunc         


        

Answer 1

var increaseBy3 = makeIncreaseByFunction(3); is the exact same as (disregarding the local storage for the variable increaseByAmount):

var increaseBy3 = function (numberToIncrease) {
    return numberToIncrease + 3;
};

So of course now you can call increaseBy3(10) and get 13. increaseBy3 just references as anonymous function which returns its first argument plus 3.