JSFiddle - React, Tailwind, and code Playground

HTML

<div>I have nothing here, check the console.</div>

JavaScript

a = [1,2,3];

Array.prototype.doMagic = function(){
    var returnvar = this;
    returnvar.push(42);
    return returnvar;
}

console.log(a);

for (var n in a){
    console.log(a[n]);
}