code: function extractPropsFromVNodeData (
    data,
    Ctor,
    tag
  ) {
    // we are only extracting raw values here.
    // validation and default values are handled in the child
    // component itself.
    var propOptions = Ctor.options.props;
    if (isUndef(propOptions)) {
      return
    }
    var res = {};
    var attrs = data.attrs;
    var props = data.props;
    if (isDef(attrs) || isDef(props)) {
      for (var key in propOptions) {
        var altKey = hyphenate(key);
        {
          var keyInLowerCase = key.toLowerCase();
          if (
            key !== keyInLowerCase &&
            attrs && hasOwn(attrs, keyInLowerCase)
          ) {
            tip(
              "Prop \"" + keyInLowerCase + "\" is passed to component " +
              (formatComponentName(tag || Ctor)) + ", but the declared prop name is" +
              " \"" + key + "\". " +
              "Note that HTML attributes are case-insensitive and camelCased " +
              "props need to use their kebab-case equivalents when using in-DOM " +
              "templates. You should probably use \"" + altKey + "\" instead of \"" + key + "\"."
            );
          }
        }
        checkProp(res, props, key, altKey, true) ||
        checkProp(res, attrs, key, altKey, false);
      }
    }
    return res
  }
docs: /*