JS Fundamentals - Closures

JavaScript

function multiplyByTwo() {
  var value = 1,
      two = 2; // two local variables
  var multiplier = function() { // inner function
      console.log("About to double: " + value);
      value = value * two;
      return value;
  }
  return multiplier;
}

var doubler = multiplyByTwo();
doubler();
doubler();
doubler();
doubler();