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CSV to Markdown Table Converter

A Node CLI that reads a CSV file and prints a GitHub-flavoured Markdown table, aligning columns and escaping pipe characters in cell values.

node --version

node csv2md.mjs sample.csv

node --test csv2md.test.mjs

Prints a Markdown table with a header row, a separator row, and one row per CSV data row.

What it does

Converts a CSV file into a Markdown table so tabular data can be pasted into a README or a pull request without reformatting. Pipe characters inside cells are escaped so the table never breaks.

import { readFileSync } from 'node:fs';

function escapeCell(value) {
  return String(value).replace(/\|/g, '\\|').trim();
}

function toMarkdown(csv) {
  const rows = csv.trim().split(/\r?\n/).map((line) => line.split(',').map(escapeCell));
  const header = rows[0];
  const separator = header.map(() => '---');
  return [header, separator, ...rows.slice(1)]
    .map((row) => '| ' + row.join(' | ') + ' |')
    .join('\n');
}

const file = process.argv[2];
if (!file) {
  console.error('usage: csv2md <file.csv>');
  process.exit(1);
}
console.log(toMarkdown(readFileSync(file, 'utf8')));

The parser splits on newlines and commas, which is enough for simple exports; quoted fields with embedded commas are called out as a limitation.

Run and verify

printf 'name,age\nAlice,30\nBob,41\n' > sample.csv
node csv2md.mjs sample.csv

Create the two-row sample file first, then run the converter; the same command works on any simple CSV export.

Expected Output

For the two-row sample the program should print a header row, a separator row, and two data rows. The output is:

| name | age |
| --- | --- |
| Alice | 30 |
| Bob | 41 |

A value containing a pipe is escaped as | so the table stays valid, and missing trailing cells render as empty columns.

Limitations

The splitter does not handle quoted fields containing commas or newlines; for those, replace the split with a stateful character parser.