[nilliams]

Opinion: nobody should be shipping any JS to oldIE, period.

Their JS engines are woeful. Even if you can get something app-like (the kind of thing you would use dart for) to work, your app won't scale w.r.t. perf so you're painting yourself into a corner.

[quarterto]

That's your opinion and you're entitled to it but people do still have to ship things for IE6-8.

[SiVal]

Some do, of course, but some of the rest of us are more interested in future advantages. If you need to target legacy browsers, legacy technologies are widely available.

If you'd like the future to be as good as possible, you might want to build new tools without the same old constraints.

[nilliams]

Understood. I'd just question if it needed JS - if JS actually added to the UX and outweighed the considerable dev cost.

[threeseed]

How on earth do you propose to implement client side functionality without JS ?

The fact is that MANY people need to support IE6-8.

[nilliams]

Sample size of 1 etc, this is just my experience.

I personally built a single page application about 2 years ago that worked in IE8, thanks to jQuery and the ecosystem of the time. jQuery, jQuery UI, various plugins incl. jsTree & DataTables.

It flew in Chrome, Firefox and Opera, even then. In IE8 it was slow as hell. Event listeners were slow, ajax and parsing JSON was slow. Everything was crazy slow. The app felt lumpy and awful. And when I hit bugs, the developer tools just were not there.

I would never do this again.

I'd wager that for IE < 8, for any non-trivial app, round-tripping to the server will give you a better UX than using JavaScript.

Deliver something usable for oldIE. There are many people that share this view. I suggest watching this talk on how the BBC deals with legacy browsers (9m 20s): http://www.youtube.com/watch?v=YfvMQ316hMU&t=00h09m20s

[amackera]

The reality is that lots of web apps must be capable of running on IE due to external restrictions (think enterprise or government).