JSLint (prior to version 2013-03-18) throws the "ADSAFE: Use the fragment option" error when the adsafe option is set to true (it's false by default) and you pass it a fragment of HTML without having set the fragment option to true. Here's an example:
This error is raised because JSLint doesn't know how to continue. Since JSLint is primarily a JavaScript parser, it doesn't expect an HTML fragment by default. The error can be fixed simply by passing the fragment option to JSLint.
In a commit on 20th March 2013, HTML, CSS and ADsafe parsing functionality was removed from JSLint. If you rely upon this functionality, you will be unable to upgrade JSLint to a version beyond that date.