Does ES6 const affect garbage collection?

Question

In Kyle Simpson\'s new title, You don\'t know JS: ES6 and beyond, I find the following snippet:

WARNING Assigning an object or array as a constan

Answer 1

WARNING Assigning an object or array as a constant means that value will not be able to be garbage collected until that constant’s lexical scope goes away, as the reference to the value can never be unset. That may be desirable, but be careful if it’s not your intent!

That note sounds a bit more of a warning than is necessary (perhaps even a bit silly) and tries to make some sort of special case out of this situation.

With a const variable declaration, you can't assign to the variable something little like "" or null to clear its contents. That's really the only difference in regard to memory management. Automatic garbage collection is not affected at all by whether it is declared const or not.

So, if you would like to be able to change the contents of the variable in the future for any reason (including to manually remove a reference to something to allow something to be garbage collected sooner), then don't use const. This is the same as any other reason for using or not using const. If you want to be able to change what the variable contains at any time in the future (for any reason), then don't use const. This should be completely obvious to anyone who understand what const is for.

Calling out garbage collection as a special case for when not to use const just seems silly to me. If you want to be able to clear the contents of a variable, then that means you want to modify the variable so duh, don't use const. Yes, manually enabling garbage collection on a large data structure that might be caught in a lasting scope/closure is one reason that you might want to change the variable in the future. But, it's just one of millions of reasons. So, I repeat one more time. If you ever want to change the contents of the variable for any reason in the future, then don't declare it as const.

The garbage collector itself doesn't treat a const variable or the contents it points to any different than a var or let variable. When it goes out of scope and is no longer reachable, its contents will be eligible for garbage collection.

const has a number of advantages. It allows the developer to state some intent that the contents this variable points to are not to be changed by code and may allow the runtime to make some optimizations because it knows the contents of the variable cannot be changed. And, it prevents rogue or accidental code from ever changing the contents of that variable. These are all good things when used in an appropriate case. In general, you SHOULD use const as much as practical.