Asynchronously check if a file exists in Node.js.

file_exists.js

//
// Callback API
//

import { access, constants } from 'fs';

const file = 'package.json';

access(file, constants.F_OK, error => {
  if (error) {
    console.log(`${file} does not exist`);
  } else {
    console.log(`${file} exists`);
  }
});


//
// Promises API
//

// import { constants } from 'fs';
// import { access } from 'fs/promises';

// const file = 'package.json';

// access(file, constants.F_OK)
//   .then(() => console.log(`${file} exists`))
//   .catch(error => console.log(`${file} does not exist`));

package.json

{
  "name": "file_exists",
  "version": "1.0.0",
  "description": "Asynchronously check if a file exists.",
  "private": true,
  "main": "file_exists.js",
  "type": "module",
  "scripts": {
    "start": "node file_exists.js",
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "Kieran Barker <kieran@barker.codes> (https://barker.codes/)",
  "license": "MIT"
}

Read the blog post.