knapsack.js

items=[{v: 5, w: 10}, {v: 1, w: 1}, {v: 3, w: 4}]

knp = (items, selected, maxWeight, val)=>{
    if (maxWeight === 0) return [val, selected];
    if (maxWeight < 0) return [0, selected];
    if (!items.length) return [val, selected];

    let last = items[items.length-1];
    let including = knp(items.slice(0, -1), selected.concat(last), maxWeight - last.w, val+last.v);
    let notIncluding = knp(items.slice(0, -1), selected, maxWeight, val);
    
    return including[0] > notIncluding[0] ? including : notIncluding;
}