What are Closures in JavaScript and how do they capture scope variables?
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EasyBasics
A closure is the combination of a function bundled together with references to its surrounding state (the lexical environment). In JavaScript, closures are created every time a function is created, at function creation time. A closure gives an inner function access to the outer function's variables even after the outer function has completed execution.
This behavior is possible because JavaScript uses lexical scoping, meaning a function's variable access is determined by its physical position in the source code. Here is a common closure demonstration:
function createCounter() {
let count = 0; // captured variable
return {
increment: function() {
count++;
return count;
}
};
}
const counter = createCounter();
console.log(counter.increment()); // 1
console.log(counter.increment()); // 2count is a private variable enclosed within the returned methods, shielded from external manipulation. This is useful for data privacy and encapsulating stateful behavior without global variable pollution.