Node Ecosystem

Readings: Node Ecosystem

The Module Wrapper

https://nodejs.org/docs/latest/api/modules.html#modules_the_module_wrapper

• Node.js wraps a modules code in a function wrapper before it is executed

   (function(exports, require, module, __filename, __dirname) {
   // Module code actually lives in here
   });
  

• Keeps top-level variables scoped to the module rather than the global object

• It helps to provide some global-looking variables that are actually specific to the module, such as:

  • The module and exports objects that the implementor can use to export values from the module
  • The convenience variables __filename and __dirname, containing the module's absolute filename and directory path

Test Driven Development (TDD)

https://jrsinclair.com/articles/2016/gentle-introduction-to-javascript-tdd-intro/

Why?

1. It forces one to think
   • What are you trying to achieve?
2. It makes debugging easier
3. It makes coding more fun

What is TDD?

• Where you write tests before you write application code
• Steps to TDD:
  • Red: Write a test and make sure it fails
  • Green: Write the simplest, easiest possible code to make the test pass
  • Refactor: Optimize and/or simplify the application code, making sure that all the tests still pass
  • Once you finish step 3, you start the cycle again by writing another test
• Writing tests
  • Write the simplest test possible first
  • Tests are written in the form: Describe [thing]. It should [do something]
  • Checking: expect(actualValue).to.equal.(expectedValue)
    • Use equal when comparing numbers, strings, or booleans, and use eql when comparing arrays or objects
  • No module code until there’s a failing test
  • When your tests pass, refactor your code

Building a JavaScript and Node.js project

https://docs.travis-ci.com/user/languages/javascript-with-nodejs

• The easiest way to specify Node.js versions is to use one or more of the latest releases in your .travis.yml

• Optionally, your repository can contain a .nvmrc file in the repository root to specify which single version of Node.js to run your tests against

• The default build script for projects using nodejs is:

  • npm test

• Travis CI uses npm or yarn to install your project dependencies

  Note that there are no npm packages installed by default in the Travis CI environment

V8

https://v8.dev/

• V8 is Google’s open source high-performance JavaScript and WebAssembly engine

Guide to ES6

https://medium.com/sons-of-javascript/javascript-an-introduction-to-es6-1819d0d89a0f#.wb7rj1gin

• Arrow functions and let keyword; Block scopes
• Classes and inheritance; Default parameters
• Destructured assignment
• Generators; Iterators; Maps
• Promises; Rest parameters; Sets
• Spread operator; Template Literals

ECMAScript 2015 (ES6) and beyond

https://nodejs.org/en/docs/es6/

• All ES6 features are split into three groups for shipping, staged, and in progress features

npm-package.json

https://docs.npmjs.com/files/package.json.html

• All you need to know about what’s required in your package.json file

How to Use npm as a Build Tool

https://www.keithcirkel.co.uk/how-to-use-npm-as-a-build-tool/

npm-scripts

https://docs.npmjs.com/misc/scripts

Videos:

TDD:

http://www.letscodejavascript.com/

NPM:

https://docs.npmjs.com/about-npm/index.html

Additional resources:

ES6 Features:

http://es6-features.org/#ClassInheritance

NPM docs:

https://docs.npmjs.com/