http://blogs.iis.net/webdevelopertips/archive/2009/06/15/tip-80-did-you-know-how-to-show-jscript-validation-errors-as-warnings.aspxWith Visual Studio 2008 RTM, JScript validation setting is an option on the HTML validation page on the Options dialog. Since Visual Studio 2008 SP1 and later, we added a new option page JScript on the Options dialog, see the blog "Introducing JScriptenCommunityServer 2007 SP1 (Build: 20510.895)