Angular function to merge two objects. This method will be in angular 1.4 but is missing in previous versions.

merge.js

function merge(dst, src) {
  var h = dst.$$hashKey;

    if (!angular.isObject(src) && !angular.isFunction(src)) return;
    var keys = Object.keys(src);
    for (var j = 0, jj = keys.length; j < jj; j++) {
      var key = keys[j];
      var src_new = src[key];

      if (angular.isObject(src_new)) {
        if (!angular.isObject(dst[key])) dst[key] = angular.isArray(src_new) ? [] : {};
        merge(dst[key], src_new);
      } else {
        dst[key] = src_new;
      }
    }

  if (h) {
    dst.$$hashKey = h;
  } else {
    delete dst.$$hashKey;
  }
    
  return dst;
}