@carnesen/mathjs-app NPM

@carnesen/mathjs-app

A full-stack app I made for a job application at a startup in 2016.

Deployed on the web at https://mathjs.carnesen.com/.

Install

Prerequisites:

Node.js version 10+

To run the application from the source code (requires git):

git clone https://github.com/carnesen/mathjs-app.git
cd mathjs-app
npm install
npm build
npm start

At that point the application should be running and serving its browser application at http://localhost:8000

How it works

This full-stack application is written in JavaScript, html, and css. The source code lives in the src directory, divided into code that only runs server side, code that only runs in the browser app, and shared "isomorphic" code. The entry point for the server-side and browser applications are src/server/index.js and src/browser/index.js, respectively.

The browser application is built on React. It allows the user to calculate mathematical expressions (e.g. "4+4") using the Math.js library. When the user submits an expression for calculation, it gets added to the right-hand column of results below the expression input box. Each expression and its result also gets sent to the back end by an http request. The back end retains a list of the ten most recent calculations submitted by all users. This list gets synchronized in real time to all connected browsers via WebSockets implemented with Socket.io. The list of the ten most recent calculations across all users shows up as the left-hand column of results below the expression input box. The state of the applications both server- and browser-side is maintained as a Redux store. Because this is a toy application unlikely to actually have multiple concurrent users, the back end simulates user activity by submitting new calculations every few seconds.