server.js

const express = require("express");
const calc = require("calc");
const app = express();
app.listen(3000, () => {
	console.log("Server running on port 3000");
});

// parse application/json
app.use(express.json())

app.get("/calculate",(req, res, next) => {
	const gen = calc.Generations.get((typeof req.body.gen === 'undefined') ? 9 : req.body.gen);
	let error = "";
	if(typeof req.body.attackingPokemon === 'undefined')
		error += "attackingPokemon must exist and have a valid pokemon name\n";
	if(typeof req.body.defendingPokemon === 'undefined')
		error += "defendingPokemon must exist and have a valid pokemon name\n";
	if(error)
		throw new Error(error)
	const result = calc.calculate(
		gen,
		new calc.Pokemon(gen, req.body.attackingPokemon, req.body.attackingPokemonOptions),
		new calc.Pokemon(gen, req.body.defendingPokemon, req.body.defendingPokemonOptions),
		new calc.Move(gen, req.body.moveName),
		new calc.Field((typeof req.body.field === 'undefined') ? undefined : req.body.field)
	);
	res.json(result);
})

app.use(express.static('dist'))