Simple csv to array demo

csvToArray.ts

const COLUMN_DELIMITER = ',';

export function csvToArray(csv: string): string[][] {
  const table = [] as string[][];
  let row = [];
  let cell = '';
  let openQuote = false;
  let i = 0;
  
  const pushCell = () => {
    row.push(cell);
    cell = '';
  };
  
  const pushRow = () => {
    pushCell();
    table.push(row);
    row = [];
  }
  
  const handleSeparator = (i: number) => {
    const c = csv.charAt(i);
    if (c === COLUMN_DELIMITER) {
      pushCell();
    } else if (c === '\r') {
      if (csv.charAt(i + 1) === '\n') {
        i++;
      }
      pushRow();
    } else if (c === '\n') {
      pushRow();
    } else {
      return false;
    }
    return true;
  }
  
  while (i < csv.length) {
    const c = csv.charAt(i);
    const next = csv.charAt(i + 1);
    if (!openQuote && !cell && c === '"') {
        openQuote = true;
    } else if (openQuote) {
      if (c !== '"') {
        cell += c;
      } else if (next === '"') {
        cell += c;
        i++;
      } else {
        openQuote = false
        if (!handleSeparator(++i)){
          throw new Error('Wrong CSV format!');
        }
      }
    } else if (!handleSeparator(i)) {
      cell += c;
    }
    i++;
  }
  if (cell) {
    pushRow();
  }
  return table;
}

console.log(csvToArray('1",2,3'));
console.log(csvToArray('"1",2,3'));
console.log(csvToArray('"1""",2,3'));
console.log(csvToArray(`"1",2,3
4,5`));
console.log(csvToArray(`"1""
",2,3
4,5`));