js401-reading

Class 01 Reading

Developer Consistency

File Name Consistency

• File names are treated differently across different systems. Use a consistent format to ensure consistent behavior
  • lower case: case sensitivity some times is used, other times not
  • kabob-case: use-this-to-ensure-spaces-are-not-a-problem
  • ALL CAPS: THIS PUTS THE FILE AT THE TOP OF THE LIST, like with README.md

Node.js

• This is an open source system with the V8 js runtime (supporting ES6/ES2015) and NodeAPIs (written in C, C++, JS)
• to handle asynchronus work, Node uses an event loop architecture that handles the processing for you

package.json

• this file configures a Node.js package
  • name and version are only required fields
  • npm init and npm init -y automate the file creation and handling of dependencies, listing them under dependencies and devDependencies

Semantic Versioning

• also known as semver
• MAJOR.MINOR.PATCH
  • MAJOR for when you make incompatible API changes
  • MINOR add backwards-compatible functionality
  • PATCH make backwards-compatible bug fixes

CommonJS modules

• CommonJS Modules allow devs to organize code in to small files of defined functionality. This is key to scalability
• anything in module.exports can be accessible to another module through the require function
• require needs a path provided to work
• modules can not be co-dependent: A needs B, but B can’t need A in turn

Test Driven Development (TDD)

• methodology for writing code with short dev cycle to speed up dev time, validate code and understand goals. 3 steps of this:
  • RED - plan code and write tests for expected behavior that should fail
  • GREEN - write code to pass specs of tests, don’t worry about optimization, test should pass
  • REFACTOR - refactor code for speed, memory, legibility
• install jest and eslint for dependencies, with a valid .eslintrc.json file and be able to run tests

Continuous Integration (CI)

• regular merging of developed features in to shared repo as they are done
• works well with automated tests, code reviews, testing support, more.

Continuous Delivery (CD)

• Deploying in short Cycles
• Code always ready to deploy
• Often paired with CI to enforce stability

Github Actions

• Github Actions is a CI system
• actions handled via rules .yml format, in the .github/workspaces in the root directory of repo with details of project (language, build/test envs, and more)
• github will automatically run tests on push/PR, enforces tests passing to merge

TDD in JS

• Devs spend more time MAINTAINING code, then writing code
• with that in mind, it makes sense to decrease maintenance rather than make it easy to write new code
• using TDD, you can decrease the subsequent cost of dev for future steps
• jest, selenium, multiple tools can be used for different testing uses
• use tools that make sense to implement - ‘new for the sake of new’ isn’t helpful, the tool has to ‘pay for itself’

About NPM

• npm let’s you publish packages/modules for others to use
• can also be used internally to re-use code across projects
• use npm client locally to upload/download on the NPM website

NPM docs

• setting up an account ont he npm site allows for uploading
• free accounts have public packages, paid accounts for private packages

Jest

• test runner for JS
• can use Babel (JS compiler) to convert your JS code to browser-compatible JS (some tools don’t work with certain browsers)
• typeScript and other features are also compatible with jest

• to use, specific test scripts need to be built

  test('description of test', () => {
    expect(2+2).toBe(4);
  });
  

  • this format creates a test, which only executes via jest, that has an input, a comparison operator, and a target value
  • tests can run specific functions, check state, check not-state, employ truthy-ness, type and more

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