JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>

JavaScript

$(document).ready(function(){
    function ViewModel(){
        this.Impossible = "impossible!";
    }
    let vm = ViewModel();
});

$(window).on("beforeunload", function (e) {
    console.log("this: " + this.Impossible);
    console.log("window: " + window.Impossible);
});