Pivot Table

Example of a pivot table using React + Typescript. Created using create-react-app.

Running locally

First install all dependencies:

npm install

or if using yarn:

yarn

After all dependencies, you can run it locally by running:

yarn start

This will run the development build of the client on localhost:3000, all while compiling styles as well as watch for any changes made to the code.

Running tests

If you want to run linting and unit tests, you can do so by running:

yarn test

This project uses eslint, and Typescript for linting as well as Jest, enzyme and react-test-renderer for unit testing.

Potential testing issue

You may run across an error when trying to run tests:

Error: fsEvents is not a function

If that's the case, please read this issue within create-react-app and follow the instructions to resolve it.

Architecture

As is with most React apps this was built using the flux architectural design

<ProductSalesByStateTable /> (is mounted - hook fires action)
|
└-+-> /actions/orders (fetch/receive orders data)
  |
  └-+-> /reducers/orders (transform to immutable records and pass to store)
    |
    └-+-> <ProductSalesByStateTable /> (accesses store, formats data)
      |
      └-+-> <PivotTable /> (recieves formatted data and renders)

In the case of this project - actions are used to fetch and pass orders to dispatchers whom then broadcasts the payload to registered callbacks with the store. The store updates as a result of the retrieved data which allows the components to (re)render.

Core technologies and libraries used

• React: core framework
• Redux: global application state maintenance
• React-redux: hooks up app framework with global state
• Typescript: type checking and linting
• Immutable.js: transforming data without mutation

Assumptions and simplifications

While working on this project, there were a few assumptions made:

1. The pivot table operation is SUM only and does not include UI sorting.
2. Data is fetched and loaded all at once (no pagination).
3. Row and column dimensions should be configurable via any string data attribute. (i.e. state, category, city, etc.)
4. Metric should only be configurable via any of these number data attributes:
   • sales
   • quantity
   • profit
   • discount

Next steps / areas to improve:

• Use more semantic HTML for table (table, thead, tbody, tr, etc.)
• Implement "sticky" column header so when a user scrolls down, the user can still see what dimension the metric belongs to.
• Adjust formatting data algorithm to allow for other operations (multiply, average, etc.)