Here are some examples of JSON documents that JsonReader fails to parse:

{ date: Date() } { date: new Date() } { date: new Date("2011-01-01") } { date: Date("2011-01-01") } { date: new Date(2011,0,1) } { date: Date(2011,0,1) }

There may be others...

While these forms would never be output by JsonWriter and are also not strictly JSON, they are commonly used and it would be helpful to support them.