Closures in JavaScript can be a tricky subject to understand at first. It's also common to be asked about closures in interviews, which is why this post aims to explain how closures work in JavaScript.
What is a closure?
According to mozilla.org, A closure is the combination of a function bundled together (enclosed) with references to its surrounding state (the lexical environment). In other words, a closure gives you access to an outer function's scope from an inner function. In JavaScript, closures are created every time a function is created, at function creation time.