// Why doesn't this work?

function whatIsInAName(first, second) {
  var srcKeys = Object.keys(second);

  return (first.filter(function(obj) {
    for (var i = 0; i < srcKeys.length; i++) {
      return (!obj.hasOwnProperty(srcKeys[i]) ||
        obj[srcKeys[i]] !== second[srcKeys[i]] ? false : true);
    }
  }));
}
console.log(whatIsInAName([{"a": 1, "b": 2, "c": 3}], {"a": 1, "b": 9999, "c": 3}));

/// --------------------- Why doesn't the above work, but the below does?

// This works
function whatIsInAName(collection, source) {
  var srcKeys = Object.keys(source);

  return collection.filter(function(obj) {
    for (var i = 0; i < srcKeys.length; i++) {
      if (!obj.hasOwnProperty(srcKeys[i]) ||
        obj[srcKeys[i]] !== source[srcKeys[i]]
      ) {
        return false;
      }
    }
    return true;
  });
}

console.log(whatIsInAName([{"a": 1, "b": 2, "c": 3}], {"a": 1, "b": 9999, "c": 3}));