Check if a file exists in Node.js

You can use existsSync:

import { existsSync } from 'node:fs';

if (existsSync('/path/to/file')) {
  console.log('Found');
} else {
  console.log('Not found');
}

If you want to avoid blocking, you can also use access. If you pass no arguments, it runs in fs.constants.F_OK mode, which will test if the given file or directory is visible to the calling process:

import { access } from 'node:fs/promises';

try {
  await access('/path/to/file');
  console.log('Found');
} catch {
  console.error('Not found');
}

Keep in mind that testing if a file exist and then opening it, is not recommended. Instead directly opening the file and handling errors is preferred (quoting the docs):

Using fsPromises.access() to check for the accessibility of a file before calling fsPromises.open() is not recommended. Doing so introduces a race condition, since other processes may change the file's state between the two calls. Instead, user code should open/read/write the file directly and handle the error raised if the file is not accessible.

posted 6 months ago

CC BY-SA 4.0

6mo ago

philipp.classen‭

46 reputation 2 2 5 6

You can check if a file exists using the fs module. Besides the methods already mentioned, you can use fs.stat(path[, options], callback) ^[1].

It's also asynchronous, and the callback returns two arguments (err, stats).

import { stat } from "node:fs";

stat("/path/to/file.ext", (err, stats) => {
  if (err) {
    // Something happened; check err.code to get details
  } else {
    // File exists
  }
});

posted 6 months ago

CC0

ɯıpɐʌ‭

144 reputation 4 3 17 2