Understanding JavaScript Closures: How Functions Remember Their Scope

Closures are a core JavaScript concept where a function retains access to variables from its outer lexical environment even after that outer function has finished executing. This works because the inner function maintains a live reference to the environment in which it was created, preventing JavaScript from discarding those variables. Lexical scope plays a key role here, as a function's accessible variables are determined by where it is written in the code, not where it is called. A practical use of closures is maintaining state between function calls, such as building a counter that increments each time the returned function is invoked. Understanding the connection between functions, lexical scope, and retained environments is essential to grasping how closures behave in JavaScript.