CSV to JSON utilities

csv-to-json.js

const fs = require("fs");

const notEmpty = (line) => line !== "\n";
const trim = (str) => str.trim();
const EOL = /\r/;
const commaReg = /, ?/;

function normalizeProp(prop) {
  const splitted = prop
    .split(" ")
    .map((word) => word.trim().toLocaleLowerCase());

  return [
    ...[splitted.shift()],
    ...splitted.map((word) => {
      let newWord = [...word].filter((letter) => /^[a-z]$/i.test(letter));
      let tmpWord = [...newWord];

      newWord[0] = tmpWord[0].toLocaleUpperCase();

      return newWord.join("");
    }),
  ].join("");
}

function readLineValues(line, lineNumber) {
  let str = line;
  let tmpStr = "";

  let values = [];

  let flag = false;

  for (let char of str) {
    if (char === '"' && !flag) flag = true;
    else if (char === '"' && flag) flag = false;

    if (commaReg.test(char) && !flag) {
      values = [...values, tmpStr];

      tmpStr = "";

      continue;
    }

    if (char !== '"') tmpStr += char;
  }

  if (flag === true) {
    throw new Error(
      "invalid format" +
        (lineNumber !== undefined ? " at line " + lineNumber : "")
    );
  }

  const trimmed = values.map(trim);

  return trimmed;
}

function csvToArray(csv, options = { enableNestedArrays: true }) {
  const [rawHeaders, ...lines] = csv
    .toString()
    .split(EOL)
    .filter(notEmpty)
    .map(trim);

  if (!lines.length) throw new Error("invalid csv!");

  const headers = readLineValues(rawHeaders).map(normalizeProp);

  const array = lines.map((item, idx) => {
    const values = readLineValues(item, idx + 2);

    const obj = headers.reduce((prev, header, idx) => {
      if (values[idx].includes(", ") && options.enableNestedArrays) {
        return {
          ...prev,
          [header]: values[idx].split(commaReg).map(trim),
        };
      }

      return { ...prev, [header]: values[idx] };
    }, {});

    return obj;
  });

  return array;
}

function csvToJSON(csv, options = { enableNestedArrays: true }) {
  return JSON.stringify(csvToArray(csv, options));
}

function csvFileToArray(file_path, options = { enableNestedArrays: true }) {
  const csv = fs.readFileSync(file_path);

  return csvToArray(csv, options);
}

function csvFileToJSON(file_path) {
  const csv = fs.readFileSync(file_path);

  return csvToJSON(csv);
}

module.exports = {
  csvToArray,
  csvToJSON,
  csvFileToArray,
  csvFileToJSON,
};