I work for a medium-small company (40-50 people) completely unrelated to IT, as a fixed-term apprentice "IT guy" (they call it "data processing center" employee). There is another employee in my office, an older man who does many IT tasks ("my PC won't turn on", "my monitor flickers", and so on) without having an IT background and with much more stuff to do. Aside from him, there's no one else to do IT (besides an external company that handles servers and security, which has consultants who are pretty expensive to call over).
So here's the problem:
Over the past few months, I have been developing a web application for the company, even though it's definitely out of my job role and my pay grade. At first I didn't mind, because I really liked doing it.
Now, though, I have received a job offer from a really good company, and am just waiting for their full official proposal to hand in my notice period.
This would be all right, if it wasn't for "Mr. X", who's not my direct superior (he's the manager of a completely different sector) but kinda is my superior. He's currently asking me to add new functionality to the web app, and these are things that would take a humongous amount of work and time.
I already told him that it would take very long (and that, besides, they would be better off giving the task to a web development company so that it gets done faster and a lot better). The matter is on hold right now, but I'm pretty sure he's going to tell me to start the task soon.
I would have preferred to wait for the official new job proposal to tell the company I'm going to quit, but apparently I might be forced to disclose the matter immediately.
What is the best way to inform my superior that I am not going to be able to add further functionality to the web app since I'm about to leave, without burning any bridges?
Keep in mind that, to add what they want to the website, they will either have to:
- Have a truckload of luck finding another employee fresh from high school capable of developing the web app
(kinda unlikely, and would take a long time since I used a technology that's not taught in high school. Also, the code is not that great, since it was my first decent-sized project)
- Hire a more experienced employee, with web development experience
(would cost a lot)
- Give the task to a web development company
(would cost a lot)
I'm not sure where to put this on a scale from "who cares, it won't be your company anymore soon" to "it was your job to write maintainable code and make it super easy to add stuff without experience and without your supervision"
N.B.: of course, this is dangerous, since I don't have an official proposal from the new workplace yet. Although I am 99% sure that they are indeed going to hire me, I'll gladly encourage answers that somehow give me a chance to wait for the proposal before telling my superiors I will quit.