This 14-video course covers closures—the bundle of a function along with its enclosing environment—and its implications on factors such as variable scopes and function references. Key concepts covered here include what makes up a closure in Javascript; learning how variables of the same name inside closures and in scopes outside them are accessed by functions; and distinguishing between variables of the same name inside functions, within closures, and ones defined in a global scope. Begin by observing how to implement counter functions with closures; how to integrate closures with buttons on web pages; and how closures can be created within objects and implications on your code. Next, learn how closures created within loops interact with variables defined within and outside the loop; how to implement getter and setter functions for Javascript objects using closures; and learn when to use prototypes for objects and how to define them. Finally, observe how to distinguish between object prototypes and classes; learn to use prototypes to implement inheritance; and implement multiple levels of inheritance with prototypes.