ofx.js

const { XMLParser } = require("fast-xml-parser");

const options = {
  ignoreAttributes: true,
  allowBooleanAttributes: false,
  parseAttributeValue: false,
  trimValues: true,
  numberParseOptions: {
    skipLike: /.*/, // Parsee all numbers as strings
  },
};

const parser = new XMLParser(options);

function sgml2Xml(sgml) {
  return sgml
    .replace(/>\s+</g, "><") // remove whitespace inbetween tag close/open
    .replace(/\s+</g, "<") // remove whitespace before a close tag
    .replace(/>\s+/g, ">") // remove whitespace after a close tag
    .replace(/<([A-Z0-9_]*)+\.+([A-Z0-9_]*)>([^<]+)/g, "<$1$2>$3")
    .replace(/<(\w+?)>([^<]+)/g, "<$1>$2</$1>");
}

// Preparing data fixing issues with special characters
function prepareData(content) {
  return content.replace(/&/g, "&amp;amp;");
}

function parse(data) {
  // firstly, split into the header attributes and the footer sgml
  const ofx = data.split("<OFX>", 2);

  // firstly, parse the headers
  const headerString = ofx[0].split(/\r?\n/);
  const header = {};
  headerString.forEach((attrs) => {
    const headAttr = attrs.split(/:/, 2);
    header[headAttr[0]] = headAttr[1];
  });

  // make the SGML and the XML
  const content = `<OFX>${ofx[1]}`;

  // Parse the XML/SGML portion of the file into an object
  // Try as SGML->XML mangling first since fast-xml-parser doesn't error on missing closing tags,
  // If that fails try normal XML
  let dataParsed = null;
  try {
    dataParsed = parser.parse(prepareData(sgml2Xml(content)));
  } catch (e) {
    dataParsed = parser.parse(prepareData(content));
  }

  // put the headers into the returned data
  dataParsed.header = header;

  return dataParsed;
}

function serialize(header, body) {
  let out = "";
  // header order could matter
  const headers = [
    "OFXHEADER",
    "DATA",
    "VERSION",
    "SECURITY",
    "ENCODING",
    "CHARSET",
    "COMPRESSION",
    "OLDFILEUID",
    "NEWFILEUID",
  ];

  headers.forEach((name) => {
    out += `${name}:${header[name]}\n`;
  });
  out += "\n";

  out += objToOfx({ OFX: body });
  return out;
}

const objToOfx = (obj) => {
  let out = "";

  Object.keys(obj).forEach((name) => {
    const item = obj[name];
    const start = `<${name}>`;
    const end = `</${name}>`;

    if (item instanceof Object) {
      if (item instanceof Array) {
        item.forEach((it) => {
          out += `${start}\n${objToOfx(it)}${end}\n`;
        });
        return;
      }
      return (out += `${start}\n${objToOfx(item)}${end}\n`);
    }
    out += start + item + "\n";
  });

  return out;
};

module.exports = {
  parse,
  serialize,
};