http://www.freecodecamp.com/minsooshin 's solution for Bonfire: Where art thou

bonfire-where-art-thou.js

// Bonfire: Where art thou
// Author: @minsooshin
// Challenge: http://www.freecodecamp.com/challenges/bonfire-where-art-thou
// Learn to Code at Free Code Camp (www.freecodecamp.com)

function where(collection, source) {
  var arr = [];
  
  function check(val) {
    var obj = {};
    for (var key in source) {
      obj = val[key] === source[key] ? val : null;
    }
    if (obj) {
      arr.push(obj);
    }
  }
  
  collection.filter(check);
  
  return arr;
}

where([{ first: "Romeo", last: "Montague" }, { first: "Mercutio", last: null }, { first: "Tybalt", last: "Capulet" }], { last: "Capulet" });