csvToJSON

#!/usr/bin/env node
let fs = require('fs')

let input = ""
let resultFilename = "output.json"
// Parse arguments
let args = process.argv.slice(2);
if (args.length != 2) {
    console.error('usage: csvToJSON <input> <output>');
    return process.exit(1);
} else {
    input = args[0];
    resultFilename = args[1];
}

/**
 * Taken from https://stackoverflow.com/a/73759785/6270354
 * @param text 
 * @param quoteChar 
 * @param delimiter 
 * @returns 
 */
function csvJSON(text, quoteChar = '"', delimiter = ',') {
    let rows = text.split("\n");
    let headers = rows[0].split(",");

    const regex = new RegExp(`\\s*(${quoteChar})?(.*?)\\1\\s*(?:${delimiter}|$)`, 'gs');

    const match = line => [...line.matchAll(regex)]
        .map(m => m[2])
        .slice(0, -1);

    let lines = text.split('\n');
    const heads = headers ?? match(lines.shift());
    lines = lines.slice(1);

    return lines.map(line => {
        return match(line).reduce((acc, cur, i) => {
            // replace blank matches with `null`
            const val = cur.length <= 0 ? null : Number(cur) || cur;
            const key = heads[i] ?? `{i}`;
            return { ...acc, [key]: val };
        }, {});
    });
}

var fileContentString = '', source = input ? fs.createReadStream(input) : process.stdin;
source.setEncoding('utf8');
source.on('data', function (data) { fileContentString += data; });
source.on('end', function () {
    let resultFileContent = JSON.stringify(csvJSON(fileContentString));
    fs.writeFile(resultFilename, resultFileContent, { flag: "w+" }, (error) => { if (error) { console.error(error) } });
})