JSON to CSV Utilities

json-to-csv.js

const fs = require("fs");

function jsonToCSV(data) {
  let json = JSON.parse(data);

  if (typeof json !== "object") throw new Error("data is not array or object");

  if (!Array.isArray(json)) json = [json];

  const keys = json.reduce((prev, obj) => {
    const objKeys = Object.keys(obj).filter((key) => !prev.includes(key));

    return [...prev, ...objKeys];
  }, []);

  return [
    keys.join(","),
    ...json.map((obj) => {
      return keys.map((key) => (obj[key] ? `"${obj[key]}"` : "")).join(",");
    }),
  ].join("\n");
}

async function jsonFileToCSV(file_path) {
  const data = await fs.promises.readFile(file_path);

  return jsonToCSV(data);
}

module.exports = {
  jsonToCSV,
  jsonFileToCSV,
};