What is a closure in JavaScript?

What is a closure in JavaScript?

• A. A closure is a function that returns another function.
• B. A closure is an array method.
• C. A closure is the global execution context.
• D. A closure is a function that retains access to its lexical scope even when executed outside that scope.

Answer: (D)

A closure is a function that retains access to its lexical scope even when executed outside that scope. In JavaScript, when a function is created inside another function, it closes over the outer variables, so those bindings stay available even after the outer function has finished.

For example, if an outer function defines a variable and returns an inner function that uses that variable, calling the returned function later will still see the original variable’s value. This happens because the inner function keeps a reference to the outer scope where those variables live, forming a closure.

This isn’t just about returning a function; it’s about the function keeping access to the outer scope’s variables. It’s also not about the global execution context or an array method.