It has been three years since this question was asked, but I am just now coming across it. Since this answer is so far down the stack, please allow me to repeat it:
Q: I am interested if there are any limits to what types of values can be set using const in JavaScript—in particular functions. Is this valid? Granted it does work, but is it considered bad practice for any reason?
I was motivated to do some research after observing one prolific JavaScript coder who always uses const statement for functions, even when there is no apparent reason/benefit.
In answer to "is it considered bad practice for any reason?" let me say, IMO, yes it is, or at least, there are advantages to using function statement.
It seems to me that this is largely a matter of preference and style. There are some good arguments presented above, but none so clear as is done in this article:
Constant confusion: why I still use JavaScript function statements by medium.freecodecamp.org/Bill Sourour, JavaScript guru, consultant, and teacher.
I urge everyone to read that article, even if you have already made a decision.
Here's are the main points:
Function statements have two clear advantages over [const] function expressions:
Advantage #1: Clarity of intent
When scanning through thousands of lines of code a day, it’s useful to be able to figure out the programmer’s intent as quickly and easily as possible.
Advantage #2: Order of declaration == order of execution
Ideally, I want to declare my code more or less in the order that I expect it will get executed.
This is the showstopper for me: any value declared using the const keyword is inaccessible until execution reaches it.
What I’ve just described above forces us to write code that looks upside down. We have to start with the lowest level function and work our way up.
My brain doesn’t work that way. I want the context before the details.
Most code is written by humans. So it makes sense that most people’s order of understanding roughly follows most code’s order of execution.