How to list files in a folder in Node

To get an array with the list of the files contained in a folder in Node.js, first import the fs built-in module, then call fs.readdirSync() passing the folder name you want to read:

import fs from 'fs'

const filenames = fs.readdirSync('content')

This returns an array of names, like ['first-post.md', 'second-post.md', 'images']. Both files and subfolders show up in the list, with no path attached. Just the names.

You can use a relative or absolute path.

Then you can iterate over the file names in this way:

filenames.map((filename) => {
  console.log(filename)
})

Filtering the list

Often you don’t want everything. When I read a content folder for a blog, I only care about markdown files. filter() handles that:

const posts = filenames.filter((filename) => filename.endsWith('.md'))

You can also exclude hidden files, the ones starting with a dot:

const visible = filenames.filter((filename) => !filename.startsWith('.'))

This matters more than it seems. macOS drops .DS_Store files everywhere, and they will show up in your list sooner or later.

Where does the relative path point?

Here’s the pitfall that bites everyone at some point. A relative path like content is resolved from the current working directory, the folder you launched Node from. Not from the folder where your script file lives.

Run node src/index.js from your project root, and content means the content folder in the root. Run the same script from inside src, and Node looks for src/content instead. You get this error:

Error: ENOENT: no such file or directory, scandir 'content'

The fix is building an absolute path based on the script location, with import.meta.dirname:

import fs from 'fs'
import path from 'path'

const dir = path.join(import.meta.dirname, 'content')
const filenames = fs.readdirSync(dir)

Now the script finds the folder no matter where you run it from. import.meta.dirname is available in recent Node.js versions; on older ones you can derive the same value from import.meta.url.

If the folder doesn’t exist at all, readdirSync() throws the same ENOENT error. Check the path before blaming the code.