JSFiddle - React, Tailwind, and code Playground

JavaScript

function f1(){

    var n=999;

    nAdd=function(){n+=1;};

    function f2(){
        console.log(n);
    }
    return f2;

}

var result = f1();
var result2 = f1();
result(); // 999
nAdd();
result2();//1000
result2();//1000
result();//999