SCRIPT5009: 'JSON' is undefined

Question

I get the following error in IE 9 SCRIPT5009: \'JSON\' is undefined only when in compatability mode. the line causing this error is

JSON.string         


        

Answer 1

JSON is not available in compatibility mode IE:

Not supported in the following document modes: Quirks, Internet Explorer 6 standards, Internet Explorer 7 standards.

Since you shouldn't be using (or worse, reyling on ) compatibility modes in the first place, you should switch IE to standards-mode by adding a valid doctype.