How do callbacks and closures relate in JavaScript?
Every callback is a closure. The callback function closes over variables from its defining scope. This is how setTimeout callbacks, map callbacks, and event handlers can access outer state when they run later.
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More FAQs in Callbacks and Event Listeners as Closures in JavaScript
Yes. Every event listener closes over variables from where it was defined. This is how a click handler can access and update a count variable defined in the enclosing function.
Yes. If a listener closes over a DOM element and the element is removed from the DOM without removing the listener, the element stays in memory because the closure keeps a reference to it.
Store the handler in a variable (not anonymous) and call removeEventListener with the same event type and the same function reference. Anonymous closures cannot be removed because you do not have a reference.
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