JSFiddle - React, Tailwind, and code Playground

HTML

<!-- The JavaScript “this” Keyword Deep Dive: Nested Functions -->

<!-- http://blog.kevinchisholm.com/ -->

<script src="http://code.jquery.com/jquery-1.11.0.min.js"></script>
<script>
var log = function(msg){jQuery('body').append('<div>' + msg + '</div>')};
</script>

JavaScript

window.music = "classical";
 
var foo = function (){
	function bar(){
		function baz(){
			function bif(){
				function billy(){
					function bobby(){
						function betty(){
							function jetty(){
								function jimmy(){
									function judy(){
										return this.music;
									}
									return judy();
								}
								return jimmy();
							}
							return jetty();
						}
						return betty();
					}
					return bobby();
				}
				return billy();
			}
			return bif();
		}
		return baz();
	}
	return bar();
};

log(this.music); //"classical" (global)

log(foo()); //"classical" (global)