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A closure in JavaScript is a function that retains access to variables from its outer scope even after that outer function has finished executing. This is possible because functions in JavaScript capture their lexical environment at creation time, not execution time .
Closures are created every time a function is defined, allowing the inner function to "remember" and access variables from the scope in which it was created, enabling data encapsulation and state persistence.
Example – Basic Closure:
function outer() {let outerVar = "I'm in the outer scope!";function inner() {console.log(outerVar);outerVar = "Updated";}return inner;}const closure = outer();closure(); // I'm in the outer scope!closure(); // UpdatedCopied!✕CopyHere, inner() forms a closure over outerVar, keeping it alive between calls .
Common Uses:
Private Variables – Hide data from the global scope:
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