JavaScript Knapsack problem

knapsack-problem.js

// http://rosettacode.org/wiki/Knapsack_problem/0-1
// list all available items
var items = [
  {name:"map", weight:9, value: 150},
  {name:"compass", weight:13, value: 35},
  {name:"water", weight:153, value: 200},
  {name:"sandwich", weight: 50, value: 160},
  {name:"glucose", weight:15, value: 60},
  {name:"tin", weight:68, value: 45},
  {name:"banana", weight:27, value: 60},
  {name:"apple", weight:39, value: 40},
  {name:"cheese", weight:23, value: 30},
  {name:"beer", weight:52, value: 10},
  {name:"suntan cream", weight:11, value: 70},
  {name:"camera", weight:32, value: 30},
  {name:"T-shirt", weight:24, value: 15},
  {name:"trousers", weight:48, value: 10},
  {name:"umbrella", weight:73, value: 40},
  {name:"waterproof trousers", weight:42, value: 70},
  {name:"waterproof overclothes", weight:43, value: 75},
  {name:"note-case", weight:22, value: 80},
  {name:"sunglasses", weight:7, value: 20},
  {name:"towel", weight:18, value: 12},
  {name:"socks", weight:4, value: 50},
  {name:"book", weight:30, value: 10}
];

var bag = items
// sort items by most value per decagram first
.sort(function (item1, item2) {
  var item1ValuePerWeight = item1.value / item1.weight;
  var item2ValuePerWeight = item2.value / item2.weight;
  return item1ValuePerWeight < item2ValuePerWeight ? 1 : -1;
})
// push items in the bag as long as the weight doesn't exceed 400 decagrams
.reduce(function (bag, item) {
  var currentBagWeight = bag.reduce(function (weight, item) {
    weight += item.weight;
    return weight;
  }, 0);
  if (currentBagWeight + item.weight < 400) {
    bag.push(item);
  }
  return bag;
}, []);

// result : compute bag weight (396)
var bagWeight = bag.reduce(function (weight, item) {
    weight += item.weight;
    return weight;
}, 0);

// result : compute bag value (1030)
var bagValue = bag.reduce(function (value, item) {
    value += item.value;
    return value;
}, 0);

// print resoult
console.log('weight: ' + bagWeight + '\nvalue: ' + bagValue + '\nitems: ' + bag.map(function (item) { return item.name; }).join(', '));
// output:
// weight: 396
// value: 1030
// items: map, socks, suntan cream, glucose, note-case, sandwich, sunglasses, compass, banana, waterproof overclothes, waterproof trousers, water