code: function equalForKeys(a, b, keys) {
    if (!keys) {
      keys = [];
      for (var n in a) keys.push(n); // Used instead of Object.keys() for IE8 compatibility
    }
  
    for (var i=0; i<keys.length; i++) {
      var k = keys[i];
      if (a[k] != b[k]) return false; // Not '===', values aren't necessarily normalized
    }
    return true;
  }
docs: Performs a non-strict comparison of the subset of two objects, defined by a list of keys.
  
  @param {Object} a The first object.
  @param {Object} b The second object.
  @param {Array} keys The list of keys within each object to compare. If the list is empty or not specified,
  it defaults to the list of keys in `a`.
  @return {Boolean} Returns `true` if the keys match, otherwise `false`.