ChrisWhealy

function factorial(n) {  
  var result = 1;
  while (n>1) {
    result = result * n;
    n = n - 1;
  }
  return result;
}

ChrisWhealy

// Calculate the nth Fibonacci number: imperative style
function fibonacci(n) {  
  var a = 0, b = 1, sum = 0;
  
  if (n<0) return NaN;
  if (n<2) return n;
  
  while (n>1) {
    sum = a + b;
    a = b;

ChrisWhealy

// Here are the kids...
var kids = [{name:"Abigail", isNaughty:false},
            {name:"Ben",     isNaughty:false},
            {name:"Clara",   isNaughty:true},
            {name:"David",   isNaughty:false},
            {name:"Emily",   isNaughty:true},
            {name:"Fred",    isNaughty:false},
            {name:"Gloria",  isNaughty:false},
            {name:"Harry",   isNaughty:false},
            {name:"Ingrid",  isNaughty:true},

ChrisWhealy

function(k) {  
  return !k.isNaughty;
}

ChrisWhealy

k => !k.isNaughty

ChrisWhealy

// Find the good ones...
var good_kids = kids.filter(k => !k.isNaughty).length;

ChrisWhealy

(acc,k) => acc + !k.isNaughty

ChrisWhealy

var nice_kids = kids.reduce((acc,k) => acc + !k.isNaughty,0);

ChrisWhealy

var naughty_kids = kids.reduce((acc,k) => acc + k.isNaughty,0);

ChrisWhealy

var naughty_and_nice = kids.reduce((acc,k) => {
    acc.nice    += !k.isNaughty;
    acc.naughty += k.isNaughty;
    return acc;
  }, {naughty:0, nice:0});