Explain closure in JavaScript.

A closer is a function inside a function that access a variable outside its scope. It is important to know a closure may or may not return a value.

Example:

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function count() {

    var i =0;  // name is a local variable created by init

    function countNum() {    // countNum() is a function inside a function, A Closure 

        i +=1;  // 'i' is a variable declared in the parent function outside countNum()   

    }

    countNum();    

}

count();