Scoring objects of arrays based on a "criteria" object

js-sort-by-score-with-lodash.js

function isArray(obj) {
  return (typeof obj !== "undefined" && obj !== null && obj.constructor === Array)
}

function areArrays() {
  if (arguments.length === 0){ return null }
  for (i = 0; i < arguments.length; i++) {
    if (!isArray(arguments[i])) { return false }
  }
  return true
}

function calculateScore(a,b) {
  if (areArrays(a, b))
    return _.intersection(a,b).length
  else
    return 0
}

// function calculateScores(criteria,item){
//   var score = 0
//   _.forEach(criteria, function(value, key) { score += calculateScore(value, item[key]) })
//   return score
// }

function calculateScores(criteria,item){
  return _.reduce(criteria, function(sum, value, key) {
    return sum + calculateScore(value, item[key]);
  }, 0);
}

var criteria = {
 a: [1], 
 b: [20],
 c: [8]
}

var items = [
  {
     a: [1], 
     b: [2],
     c: [4]
  },
  {
     a: [10],
     b: [23],
     c: [9]
  },
  {
     a: [2],
     b: [20],
     c: [8]
  },
  {
     a: [1],
     b: [20],
     c: [8]
  }
]

scores =_.map(items, function(item) {
  return calculateScores(criteria, item);
}, 0);

console.log("scores", scores)

filtered_items = _.filter(items, function(item) { return calculateScores(criteria, item) > 0; });
sorted_items = _.sortBy(filtered_items, [function(item) { return -calculateScores(criteria, item); }]);

console.log("sorted_items", sorted_items)

var expected_result =  [
   {
     a: [1],
     b: [20],
     c: [8]
    },
    {
     a: [2],
     b: [20],
     c: [8]
    },
    {
     a: [1], 
     b: [2],
     c: [4]
    },
];

console.log("Does it work?", _.isEqual(sorted_items, expected_result))