In the previous article on closures in javascript, we learned that Closure is one of the most important yet most misunderstood concepts in Javascript. The closure is a methodology in which a child function can keep the environment of its parent scope even after the parent function has already been executed, we can say it otherwise to remember or recreate the scope and its members that already have been executed once.

JavaScript Modules: These are the best implementation of Closure. Modules are small units of independent, reusable code that are desired to be used as the building blocks in creating a non-trivial Javascript application. Modules let the developer define private and public members separately, making it one of the more desired design patterns in the JavaScript paradigm. You may see modules as Classes as in any other Object-Oriented Programming Language.

Note: In ES2015, the class keyword was used to define classes in Javascript, but even though JavaScript still stands tall to be a classless programming language while ES2015 classes are basically special functions. Coming back to Modules let us first see one example to see what Modules can do, we will try to simulate the behavior of a Rectangle Class giving in the length of two sides and getting back the area.