asyn_callback.js

(cb=>{
//setTimeout() wraps the callback cb and makes it run in 
//another execution context, or "thread"
//the term thread is not accurate but may provide some ease of understanding
//the different contexts that help to achieve asynchrony
			setTimeout(()=>{
				cb()
				},0);
	console.log("B")
	})(()=>{
		console.log("C")
		});
		console.log("A");