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

bonfire-where-art-thou.js

// Bonfire: Where art thou
// Author: @nirajkrz
// 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 = [];
  // What's in a name?
   var keys = Object.keys(source);
  // Filter array and remove the ones that do not have the keys from source.
  arr = collection.filter(function(obj) {
    //Use the Array method every() instead of a for loop to check for every key from source.
    return keys.every(function(key) {
      // Check if the object has the property and the same value.
      return obj.hasOwnProperty(key) && obj[key] === source[key];
    });
  });
  return arr;
}

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