Why Modules?

What this Book Covers

• Objects as Modules - The book starts with the creation of a simple module which returns a single object. A factory based module is introduced that can create multiple objects. Learn how to seal an object to protect it from changes.



• Properties - The next step after defining objects is to add properties. Learn how to add properties that can be enumerated and protected against invalid values.



• Methods - Methods are what functions are called when they are part of an object. Define methods that can accept named parameters. Learn how to chain methods together and guard against invalid parameters.



• Module Parameters - Modules can be passed parameters, just like a functions or methods. Learn how to pass parameters to a module or a factory function to construct objects.



• Named Exports - Instead of returning the whole module, only return part of it. Learn how to export named objects and functions and special techniques for naming factory related exports.



• Inheritance - Modules and objects can be derived from other modules and objects. Learn how to derive and combine objects and override methods in parent objects.



• Callbacks - When using third party libraries with callbacks, care must be taken to integrate them into a module. Learn how to create modules that wrap existing callbacks and define new callbacks.



• Promises - Callbacks calling callbacks calling callbacks can get out of hand. Learn how to create modules that wrap third party callbacks in promises and define new promises.



• Unit Testing - When making changes to a module it is handy to be able to run a suite of tests to make sure that nothing broke. It’s also helpful to make sure that new functionality works as expected. Learn how to create and run unit tests against modules.

What this Book Covers

• Node Package Manager - The book starts out by introducing the Node Package Manager (npm for short). After a brief overview, instructions are given on how to install the npm tool and how to add a user to the npm site. The npm site is where you can publish your packages.


• Calculator Example - Even though the book is about publishing and not programming, you will need to have something to publish. This chapter provides a simple calculator module that you are free to use, modify and publish.


• Creating a Package - Setup your project and turn it into a package using the npm command line tool. Learn about the special package file that the tool generates. Create an ignore file to control what actually goes into your package. Once you are familiar with the steps, you will be able to turn any module into a package.


• Unit Testing - Learn how to use two popular tools to build test suites for your project. You will also learn about another tool that lets you monitor the live effect of source code changes while you are working.


• Source Control - Get an introduction to the popular source control tool called git. Learn how to publish the source code for your package to github.com.


• Documentation - Document your work with a README file. Get started with an introduction to the Markdown syntax. Learn by example what sections a package README file should have and what they should look like.


• Publishing a Package - Once you know how to build, test, document and check your package code into source control, you will be ready to publish it. Walk through the steps to put your package online.


• Creating Examples - Documentation is great, but example code is even better. Add examples to your project in a way that will make them easy to find.


• Publishing Updates - When updating your package, learn how to apply the rules of semantic versioning to your build numbers. Then remember to add new tests, document the version history and push the changes to source control.


• Creating a Command Line Utility - As a bonus chapter, this book also covers using JavaScript and npm to create a command line utility.