Chrome and Safari have a REPL console - you can type JavaScript and get immediate feedback. As do Firefox (with Firebug) and Opera (Dragonfly). The mental mode

Chrome and Safari have a REPL console - you can type JavaScript and get immediate feedback. As do Firefox (with Firebug) and Opera (Dragonfly). The mental model of raw client side JS, along with actually saving your code isn't exactly "instant gratification" though. This should be a web service that lets you easily save your code, and gets rid of most of the accidental browser complexity. And while we're at it, you should be able to embed the stuff you made elsewhere, hosted or not. (though IE throws a spanner in the works if you're using Canvas and want to embed it to show others) This is sounding better and better the more I think about it.