Sprint Challenge: Advanced React

Intro

In this challenge, you will write the logic for THIS WIDGET.

Study its functionality and also inspect the Console, the Network tab and the Elements tab in Chrome Dev Tools:

• There are two versions of the widget with identical functionality: class-based and functional.
• The input box at the bottom of the page expects a valid email address.
• Email validation errors arrive from the server, as you can see in the Network tab, under "Preview".
• The payload sent to the server on form submit can also be seen in the Network tab, under "Payload".
• One valid email in particular, [email protected], results in a "Forbidden" server error❗
• The origin of coordinates of the grid is on its top-left corner.

Requirements

Tools

• Node >= 18.x
• NPM >= 9.x (update NPM executing npm i -g npm)
• Unix-like shell (Gitbash/bash/zsh)
• Chrome >= 100.x

❗ Other configurations might work but haven't been tested.

Project Setup

• Fork, clone, and npm install. You won't need to add any extra libraries.
• Launch the project on a development server executing npm run dev.
• Visit your widget by navigating Chrome to http://localhost:3000.
• Run tests locally executing npm test. The test files are codegrade_mvp.test.js and App.test.js.

API

• The application includes an endpoint reachable at POST http://localhost:9000/api/result.
• You can experiment with this endpoint using an HTTP client like Postman.
• The endpoint expects a payload like { "x": 1, "y": 2, "steps": 3, "email": "[email protected]" }:
  • x should be an integer between 1 and 3.
  • y should be an integer between 1 and 3.
  • steps should be an integer larger than 0.
  • email should be a valid email address.
• Expect an "Unprocessable Entity" server response if the payload has the wrong shape.

MVP

MVP 1, The Grid

• Replicate the functionality and DOM shown in the prototype linked at the top of this README.

• Keep your code inside frontend/components/AppFunctional.js.

• The component exposed by AppFunctional.js must be a stateful functional component.

• The component in AppClass.js is optional but can be tackled if desired. It's not required to pass the sprint.

• The DOM produced by AppFunctional must match exactly the DOM in the prototype:

  • The hierarchy of HTML elements, their ids, class names etc must be the same.
  • The current square is marked with a capital B and an "active" class name.
  • The submit success and error messages that display on the page come from the API (see Network tab).
  • No frontend form validation code is required.

• The coordinates of each square of the grid are as follows:

    (1, 1) (2, 1) (3, 1)
    (1, 2) (2, 2) (3, 2)
    (1, 3) (2, 3) (3, 3)

❗ ALL TESTS MUST PASS

MVP 2, Testing

• Using codegrade_mvp.test.js as inspiration, write 5 tests inside frontend/components/App.test.js:
  • From inside the test file, import AppFunctional.js.
  • Test that the visible texts in headings, buttons, links... render on the screen.
  • Test that typing on the input results in its value changing to the entered text.

Regarding Grids and Other Notes

• Inside AppClass.js and AppFunctional you will find some suggested states and helper functions. Feel free not to use them.

• You don't need a complicated structure to track the state of the grid, because we aren't storing any information in the cells.

• Imagine that the grid were simply a one-dimension array broken --only visually-- into three rows.

• The only component state you need in order to drive the grid is an integer from 0 to 8: the index the "B" is at.

• Other pieces of information, like coordinates, can be derived from that index, and don't need a state of their own.

• If you want to make life more complicated (or interesting) for yourself, other structures can be used to store the state of the grid:

  // A plain array can be used to represent a grid.
  // But our App component needn't track the whole array, only the index where the "B" is.
  [null, null, null, null, "B", null, null, null, null]
  
  // 2D arrays or matrices can be used to represent a grid, but this is not recommended in this project:
  [[null, null, null], [null, "B", null], [null, null, null]]
  
  // A string also could work, but strings in JS are immutable making this approach inconvenient:
  "xxxxBxxxx"

• "Product" works hard designing the messages: we must reproduce them faithfully, down to the last comma.

• ❗ Remember only the functional version is required; the class-based one is recommended but optional.