Sally and Joe are two love birds. They shared everything with each other and soon enough it was almost impossible to think that anything could come between them. One day, they had a quarrel which built up to a break up.  It was hard for Joe and he wanted

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Closure in JavaScript refers to the concept of a child function retaining access to variables declared in its parent scope even after the parent function has completed its execution.

How Do Closures Work in JavaScript? Explained with Code Examples

function hii(msg){
const ps = msg;
return (arg) =&gt; {
// this log statement uses ‘ps’ variable of parent scope of function
console.log(ps, arg);
}
}
//once we call this ‘hii’ function here it return the another function
//now ‘hii’ function is completed execution
const cb = hii(“Hello”);
// when we call returned callback function it will still have value of ‘ps’ variable even after the ‘hii’ function is terminated
cb(“world”);

Have 15 years of experience in web development, and somehow this interview question still gives me the creeps :D

A closure in programming refers to the bundling of a function along with its lexical environment, allowing it to retain access to variables from its containing scope even after that scope has finished executing. This enables powerful patterns like callbacks and encapsulation in languages that support it, such as JavaScript.

I am learning to code, and I personally found the introduction to this article confusing. The multiply examples, were very poor examples, akin to that foo bar nonsense on the MDN. It was only at the end of the article, with the revelation of the ‘Sally and Joe’ example, that the true nature of closures were revealed.
Interestingly, I had been using closures in my code, without even realising. In my case, whilst learning event listeners, I quickly discovered that I did not like declaring them outside of the scope. I prefer them encapsulated within a function that requires them.Therein lies the closure.
I am studying classes now, and conceptually, closures are not too dissimilar to class constructors. Both provide a mechanism for storing private variables, and both have functions (methods) that work on those variables.