Function _merge

06.Router/basic/js/vue-resource.js:393–407

(target, source, deep)

  }

  function _merge(target, source, deep) {
      for (var key in source) {
          if (deep && (isPlainObject(source[key]) || isArray(source[key]))) {
              if (isPlainObject(source[key]) && !isPlainObject(target[key])) {
                  target[key] = {};
              }
              if (isArray(source[key]) && !isArray(target[key])) {
                  target[key] = [];
              }
              _merge(target[key], source[key], deep);
          } else if (source[key] !== undefined) {
              target[key] = source[key];
          }
      }
  }

  function root (options, next) {