This past summer I swung by Y Combinator a couple times to scope out the new startups. (Fun fact! I was in Y Combinator during the Summer of 2006.) Out of all the startups there one really caught my eye: AppJet.

They were setting out to build a quick-and-easy way to construct web applications using, their language of choice, JavaScript. They were doing all of this using Rhino, giving each application its own instance to play with. I met up with them to discuss things, how apps were going to be built, what standard libraries to provide; they were on a good track, and by the look of today’s launch, they were quite successful.

Just to list some really-cool things that they’ve done:

• They have a full browser-based, syntax-highlighted, IDE for building the applications
• Each application has its own sub-domain and controlled Rhino instance.
• They have a, really nice, comprehensive API reference.
• You can build dead simple Facebook apps.
• They have persistent server-side storage.
• There’s a public app directory that you can browse.

Just to give you a taste, here’s the full source code to a “shoutbox” application. (Remember, this is server-side/client-side mixed!)

import("storage");

var historySize = 20;

if (! storage.msgs) {
    storage.msgs = new StorableObject();
    storage.start = 0; // first msg
    storage.end = 0; // index after last msg
}

if (request.isPost) {
    var newText = request.params.newText;
    storage.msgs[storage.end++] = request.params.newText;
    while (storage.end - storage.start > historySize) {
        delete storage.msgs[storage.start++];
    }
    response.redirect("/");
} else {
    print(FORM({id:"shoutform",action:"/", method:"post"},
          INPUT({type:"text", name:"newText", size:40}),
          INPUT({type:"submit", value:"shout!"})));
    var messageDiv = DIV({id:"msgs"});
    for(var i=storage.end-1; i >= storage.start; i--) {
        messageDiv.push(P(storage.msgs[i]));
    }
    print(messageDiv);
}

I’m very impressed: Congrats David, Aaron, and J.D.!