For musteriuz: Java and JavaScript are entirely different things. The engine that interprets JavaScript is in the browser you use, no other way to update it (that I know of). Java is... better off not installed at all unless you really need it, considering the quite few uses it usually has anymore and the potential security risks.

For Alaric.us: You asked someone else, but let me butt in a bit: Since MS decided not to let newer versions of IE also work on Vista and musteriuz said that's what he uses, that's the limit. And there are reasons to prefer IE. I also use it, v11 of course since I'm on Win 7 (and just recently got pestered by another dev about it, that ended badly).
My reasons for sticking to IE are... Let's see, entirely random order:
- I not only don't need but specifically don't want add-ons, so the fact that the others accept far more is not any sort of advantage, but actually means they may be tampered with more.
- It doesn't automatically update, like Chrome does. There will not be things with automatic updates (except of course an option that you can see and set to off (if not off by default) right away and trust it to stay that way) on my computer. Top reason to stay well away from Win 10 too.
- Actually, no frequent annoying updates in general. It's handled through Windows Update and with the rare exception of a critical security update released out of cycle its updates come along with the rest on Patch Tuesday every month, and it's usually security and bugfixes (though at times they create bugs as well, to be fixed the next month or even 2 months later), not messing with other stuff.
- It has a bunch of settings you can easily access in the old fashioned way, which generally let you know more or less what they do by name and/or description. When I had a look at Chrome, there was next to nothing there. Firefox has a fair few less in that format and while there are a lot more in about:config that's not intuitive at first and then you have to look up what each of those things does or what to search for to change what you want, no explanations built in.
- Doesn't syncronize, ask to log on, etc. elsewhere.
- With a right click in the tab area I can right away see the list of the recently closed tabs and pick which one to reopen or just glance at it to remember what I had open, see a title again, whatever I need. On FF I can just reopen the last closed tab, and back when I tried Chrome this recently closed tabs list was only available on the new tab page.
- There's an obvious setting to set the new tab page to be the same as the homepage. In FF you could customize the new tab page separately too, but only from about:config and they removed that ability a few versions ago with a senseless explanation, so now I need an add-on to do something as basic as having the same custom page load both when I first open the browser and as new tab page. On Chrome again as far as I'm aware this requires add ons.
- It requires far less processing power than Firefox. May be brought down by script-heavy pages, there are some it crawls on, but I try to avoid those because it's a nasty practice (ahem!) in general, so what I notice is for example while watching videos or streams, I can have 5-10% CPU use on IE and 20-40% on FF.
- To be worth the "cost" of adapting to something other than what you're used to and does a good enough job, that something else would need to be clearly superior in every way by a significant margin. From the above, for my uses, that's not the case with the current options. So that also leads to my answer to what a dev may do to convince me to switch to another existing browser: Nothing. Won't happen. So maybe make a new one that's clearly better than IE in the ways I care about and doesn't have any of the negatives that keep me away from FF or Chrome now and then try that convincing part. (And same goes for any other switches or "upgrades".)