jQuery-UI is the official jQuery user interface library. Prior to version 1.13.0, accepting the value of the `of` option of the `.position()` util from untrusted sources may execute untrusted code. The issue is fixed in jQuery UI 1.13.0. Any string value passed to the `of` option is now treated as a CSS selector. A workaround is to not accept the value of the `of` option from untrusted sources.