JavaScript’s implementation of scope and context is a unique feature of the language, in part because it is so flexible. Functions can be adopted for various contexts and scope can be encapsulated and preserved. These concepts are behind some of the most powerful design patterns JavaScript has to offer. However, this is also a tremendous source of confusion amongst developers, and for good reason. The following is a comprehensive explanation of scope and context in JavaScript, the difference between them, and how various design patterns make use of them.
A great post about the the fundamentals of Javascript and some concepts hadn't even quite grasped including the ability to execute any function in any desired context via Call and Apply
flippinawesome.org/2013/08/26/understanding-scope-and-context-in-javascript/