Explaining JS closures

closure.js

// before anything is done to the multiplier function
// it looks like this:
function multiplier(factor) {
  return function(number) {
    return number * factor;
  };
}

var twice = multiplier(2);
// Once the multiplier function gets set,
// this is what the multiplier function looks like:
function multiplier(2) {
  return function(number) {
    return number * 2;
  }
}

// When you assign the result of the multiplier function
// to a variable, it looks like this:

function twice(number) {
  return number * 2; // 2 is frozen in place from the multiplier function
};

// Then when the twice function is called it looks like this:
twice(5) {
  return 5 * 2;
}