Forwards-compatible syntax proposal

[Nathan de Vries]

On Mon, 2008-05-26 at 10:22 -0400, Mike Shaver wrote:
> > The main reason I'm interested in an ES4 script accessing an ES3
> > script (I presume the the reverse is not possible?)
> 
> The reverse is indeed possible.

Is there any reading material you could point me to as to how this would
work? I thought the entire purpose of versioned <script /> tags was to
allow vendors to evaluate one script as ES3 and another as ES4. In that
context:

  <script type="application/javascript">
  /*<![CDATA[*/
    var ES3ProtoClass = Class({
      initialize: function() {
        this.es4instance = new ES4Class;
      }
    });
  /*]]>*/
  </script>
  
  <script type="application/javascript;version=2">
  /*<![CDATA[*/
    class ES4Class() {
      private const es3instance;
      
      function ES4Class() {
        es3instance = new ES3ProtoClass();
      }
    }
  /*]]>*/
  </script>

What does "new ES4Class" mean to a user agent that does not yet support
ES4, or one that supports both ES3 & 4, but treats "app/javascript" as
ES3.

Am I missing something?


Regards,

--
Nathan de Vries