Adder

A simple project for adding and calculating expressions of the form Axᵃ + Bxᵇ + .... Written in TypeScript, linted with ESLint. Express.js server. Mocha + SuperTest tests.

Getting up and running

Clone or download this repository and cd into its directory. Run npm install to install all dependencies. After that's done, you can use the following commands:

• npm run compile to compile TypeScript into usable JavaScript
• npm run lint to lint TS
• npm start to start server
• npm test to compile TS and then run all tests
• npm run develop to compile TS, run all tests and start server – all in one
• npm run cli to sum or calculate expressions from the command line, no server

You can get debug information printed by setting shell variable DEBUG like this:

• export DEBUG="*" to see all debug information
• export DEBUG="adder:*" to only see information specific to this project

Or you can change server port from the default 3000 to, say, 999 by setting shell variable PORT like this export PORT="999".

Data format

The raw representation of an expression is an array of [power, coefficient] tuples (TS type [number, number][]), e.g.:

• 2137*x^2 + 1337 (2137*x^2 + 1337*x^0) is [[2, 2137], [0, 1337]]
• x - 777*x^(-3) (1*x^1 + (-777)*x^(-3)) is [[1, 1], [-3, -777]]

Internally that is stored as a power => coefficient map.

API endpoints

Sum Expressions

GET /sum

Request – application/json

field	type	description	default
expressionsRaw	[number, number][][]	array of expressions to be summed	required

Response – application/json

field	type	description
expressionRaw	[number, number][]	expression that is the sum of all given
expressionString	string	string representation of the sum

or

field	type	description
error	string	error message

Calculate Expression

GET /calculate

Request – application/json

field	type	description	default
expressionRaw	[number, number][]	expression to use for calculation	required
variableValue	number	input value (x)	required

Response – application/json

field	type	description
result	number	result of the calculation

or

field	type	description
error	string	error message