code: function createMarkupForCustomAttribute(name, value) {
      if (!isAttributeNameSafe(name) || value == null) {
        return '';
      }
      return name + '=' + quoteAttributeValueForBrowser(value);
    }
docs: Creates markup for a custom property.
  
  @param {string} name
  @param {*} value
  @return {string} Markup string, or empty string if the property was invalid.