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title dateModified dateCreated tags parent week topics content
Week-06
2024-10-15
2024-08-20
react
[[Intro to React V3]]
6
project organization
refactoring
reusable components
testing
lesson plan

Week-06

[!drafting note] #drafting-note we will probably expose the students to a repo that has pre-written tests rather than write their own. This week will probably have 2 submissions

[!drafting note] #drafting-note We've sit on props destructuring assignment for this week

  1. submission #1 - code updates to refactor project
  2. submission #2 - diagnose 3-4 failed tests, stretch goal: write test for a component

Introduction

Topics Covered

  • Reusable Components
  • Refactoring
  • Project Organization
  • Testing

Lesson Objectives

By the end of this lesson, we will:

Objective 1: Reusing Components

[!drafting note] #drafting-note Take advantage of the variants property: phones have models, shirts, hats, jackets have different colors This may be a good way to deal with optional props with default values

  • Discuss the value of reusable components and how they foster efficiency, scalability, and consistency in React development
  • Implement reusable components that can be shared across an application

Objective 2: Refactoring out Sub-components

  • Examine how refactoring out portions of an existing component into re-usable components improves code organization and readability
  • Demonstrate the process of extracting logic and elements from components to craft sub-components

Objective 3: Organizing Files in a React Project

  • Discuss essential methodologies for effective file organization in a React project
  • Formulate an approach to organize our project

Objective 4: Testing React Components

  • Discuss the fundamental importance of testing to ensure functionality, robustness, and stability in React components
  • Compare various testing methodologies like unit testing, integration testing, and end-to-end testing
  • Use Jest and the React Testing Library to test React components and troubleshoot bugs

Discussion Topics

Reusing Components

  • keeps code dry - write once and instantiate as many instances as needed
    • certain elements tend to repeat themselves
      • may be styled differently but contain the exact same content
        • navigation menus
        • social media sharing buttons
      • may have the same structure but contain different data
        • they differ only in the data that is provided through props
        • product cards in a grid
        • gallery of profile cards
          • each card contains same characteristics - name, profilePicture, location, motto, etc.
        • list items
        • error, info, success, and warning dialogs
  • instances configured through props
    • affect content, layout, color, even positioning
    • example props in action
      • dialogs: message, type (error, info, warning), callback
      • profile cards: name, profilePicture, location, motto, profileUrl
    • discuss setting default values
  • component libraries provide re-usable components that:
    • can be used 1 or more times in an application
    • provide styling or animation through component definition
    • solve common accessibility or internationalization challenges
    • implement challenging layouts or complex behaviors
      • tables
      • calendars
      • carousels

Refactoring Out Sub-components

  • Components can split the application to organize its layout
    • each page/pane/screen should be its own component - we will call them "features"
      • props can be used to pass on application-wide state but may not be needed
    • features tend to be splittable into smaller, sub-blocks
      • headers and footers are common across web pages
      • single main, sidebar but could still be worth being its own component
      • #placeholder/demo-code 2 examples splittable features from [[[Code-Along - eCommerce Store]]]
      • features tend to be areas where state is managed
  • Smaller feature or elements that appear in more than one place
    • cluster of social media share buttons
  • State used across components siblings needs to be managed by the common ancestor
    • could be a parent, a parent of a parent, or deeper
    • implement useState in common ancestor then pass variable and updater function to sub-component instance
  • Maintain local state and communicate major changes up
    • local state to sync user input to what is being displayed
    • invoke a callback that communicates changes to parent who manages application state
  • 1 component for 1 purpose - within reason

Organizing Files in a React File

Note

There are a lot of discussions and even more opinions about how to structure projects. What we provide here is a sensible approach that works well with small to medium React projects. Larger projects or those that use prominent frameworks such as Next.js, Astro, Remix may need a different approach to organizing code.

  • explore [[Code-Along - eCommerce Store]]

[!drafting note] #drafting-note Clean the directory up to match the CTD Swag

.
├── node_modules/
├── public/
	└── vite.svg
├── src/
    ├── assets/
	    └── react.svg
    ├── features/
	    ├── About.jsx
	    ├── Account/
		    ├── Profile.jsx
		    └── Orders.jsx
	    ├── Account.jsx
	    ├── Checkout.jsx
	    └── Store.jsx        
    ├── services/
	    └── localStorage.js
    └── shared/
	    ├── Footer.jsx
	    ├── Header.jsx
	    ├── NavigationMenu.jsx
	    └── Cart.jsx
├── .eslint.cjs
├── .gitignore
├── .prettierignore
├── .prettierrc
├── index.html
├── package-lock.json
├── package.json
├── README.md
└── vite.config.js
  • group files by usage
  • public/
    • static resources not used in code
    • files that need their file name to remain unchanged
    • content that is accessed by URL but not imported into application
  • src/ contains majority of working files
    • assets/ - static resources that code needs to import
      • images (.jpg, .png, .svg, etc), json, csv, etc.
      • file names get hashed in production
        • programmatically ensures file names are unique
        • helps with cache busting
      • plugins available to optimize files (we will not use any of these)
        • image dimensions
        • compression
    • features/ - pages of a website or whole screens of the app
      • About, Account , Checkout, and Store components
      • each feature can be broken into sub components
        • if used only in that feature, create a folder with the name of the feature
          • Account.jsx + Account/
        • if used elsewhere, place in shared
          • Footer, Header, NavigationMenu, Cart
    • services/ - non-React functionality extracted from components
      • external connectivity: API calls, WebRTC connections, local storage
      • adapters to 3rd-party libraries
      • user authentication
    • shared/ - re-usable components that can be used anywhere
      • common page elements

Testing React Components

[!drafting note] #drafting-note This section NEEDS attention

React Testing Library Tutorial (Robin Wieruch) What tools do we need

  • Jest (optionally Vitest)
  • React Testing Library (replacement for Enzyme)
  • purpose of testing
  • types of testing methodologies
    • unit - individual parts in isolation
    • integration - ensure components work together as a group or as a larger feature
    • end-to-end - tests that run across an entire stack that replicate user tasks to ensure functioning
  • testing in React - focus on unit and integration tests
    • ensure rendering under different conditions
    • uses, updates state correctly
    • handles events correctly
    • not every function or component needs a test
    • test for functionality, not implementation
      • Testing Library reenforces this by working with DOM nodes, not component instances
  • steps to testing
    1. install & configure test tools
    2. determine what to test
    3. write test
    4. run
    5. examine the output

Weekly Assignment Instructions

Expected App Capabilities

After completing this week's assignment, the app should be able to:

  • capability 1
  • capability 2
  • capability n

Instructions Part 1

  1. step 1
  2. step 2
  3. step n

Instructions Part 2

  1. step 1
  2. step 2
  3. step n

Instructions Part n

  1. step 1
  2. step 2
  3. step n

References and Further Reading

Reusable Components

Refactoring

Project Organization

Testing React Components