For understanding callback hell better... and inversion of control.

cb.js

var cbFn = function() {
	console.log('Done')
}

// Run Async API call
completeAsyncCheckout(data, cbFn);

cbFn = function() {
	// Guessing it prints 'Finished' since it has reference.
	console.log('Finished');
}

// In this scenario: 
// Have this qn because from your talk - 'Syncing Async' you mentioned that due to inversion of control they could potentially call the cbFn multiple times.
// Wondering how that could happen?
// The callback is called once the request completes right? Or is there a way a callback can be triggered multiple times once a request is complete?
// What controls how many times the success callback will be called? 

@getify Gotcha.. Thanks a lot. You're my JS hero!