Ben Cherry, web developer at Twitter, takes us step by step through the Module Pattern. He introduces the standard features of Anonymous Closures and avoiding global scope, and covers advanced concepts such as augmentation, cloning, inheritance, private state and sub-modules.
A simplified explanation of closures by Morris Johns: A closure is the local variables for a function - kept alive after the function has returned.
A clever hands-on interactive mini-course by Nathan Whitehead that guides you through bite-sized chunks from variables, to functions, to return values, to functions as first-class objects and right into closures and finally continuations. The hands-on exercises are JS Linted and unit-tested which gives you ample space to try out your new-found knowledge.