JSFiddle - React, Tailwind, and code Playground

JavaScript

function a() {
    console.log('a', this);
}

function Obj() {
    var b = function() {
        console.log('b', this);
    }
    this.c =  function() {
        console.log('c', this);
    }
    b();
    this.c();
}
a();
var o = new Obj();
o.c.call(window);