UnderstandingClosure.js

// Sample 1
function wrapValue(n) {
  var localVariable = n;
  return function() { return localVariable; };
}

var wrap1 = wrapValue(1); /* invoke wrapValue with argument 1(n on parameter), 1 will then be assigned to the localVariable.
                             Remember that wrapValue returns a function, so it's like you're assigning a function to wrap1 that 
                             returns the localVariable value, in this case, 1. */
var wrap2 = wrapValue(2);
console.log(wrap1()); // invoking wrap1 will return 1, this logs 1 on the console
// → 1
console.log(wrap2());
// → 2

// Sample 2
function multiplier(factor) {
  return function(number) {
    return number * factor;
  };
}

var twice = multiplier(2); // the return value of invoking multiplier(2) will be assigned to variable twice, it will return:
                                function(number) {
                                  return number * 2;
                                };
console.log(twice(5)); 
// → 10