Sunshine hours calculator

solar.js

/**
 * Sunshine hours calculation. Data taken from https://cliflo.niwa.co.nz.
 *
 */

const fs = require('fs');
const readline = require('readline');

const linestream = readline.createInterface({
    input: fs.createReadStream(process.argv[2]),
    output: process,
    console: false
});

const reduced = {};

linestream.on('line', line => {
    if (!line.startsWith("Wellington")) return; 

    const values = line.split(',');
    const year = values[2].substr(0, 4);
    const month = values[2].substr(4, 2);

    initializeMonthAndYear(year, month);
    addToMonthAndYear(year, month, values[3]);
});

linestream.on('close', () => {
    Object.entries(reduced).forEach(([k,v]) => {
        console.log(`Year ${k}: ${v['01'].toFixed(1)} sunshine hours.`)
    });
});

/**
 * 
 * @param {*} year 
 * @param {*} month 
 */
const initializeMonthAndYear = (year, month) => {
    if (!reduced.hasOwnProperty(year)) {
        reduced[year] = {};
    }

    if (!reduced[year].hasOwnProperty(month)) {
        reduced[year][month] = 0;
    }
}

/**
 * 
 * @param {*} year 
 * @param {*} month 
 * @param {*} sunshineTotal 
 */
const addToMonthAndYear = (year, month, sunshineTotal) => {
    reduced[year][month] += parseFloat(sunshineTotal);
}