Node.js check if file exists

Edit: Since node v10.0.0we could use fs.promises.access(...)

Example async code that checks if file exists:

function checkFileExists(file) {
  return fs.promises.access(file, fs.constants.F_OK)
           .then(() => true)
           .catch(() => false)
}

---

An alternative for stat might be using the new fs.access(...):

minified short promise function for checking:

s => new Promise(r=>fs.access(s, fs.constants.F_OK, e => r(!e)))

Sample usage:

let checkFileExists = s => new Promise(r=>fs.access(s, fs.constants.F_OK, e => r(!e)))
checkFileExists("Some File Location")
  .then(bool => console.log(´file exists: ${bool}´))

expanded Promise way:

// returns a promise which resolves true if file exists:
function checkFileExists(filepath){
  return new Promise((resolve, reject) => {
    fs.access(filepath, fs.constants.F_OK, error => {
      resolve(!error);
    });
  });
}

or if you wanna do it synchronously:

function checkFileExistsSync(filepath){
  let flag = true;
  try{
    fs.accessSync(filepath, fs.constants.F_OK);
  }catch(e){
    flag = false;
  }
  return flag;
}

Consider opening the file directly, to avoid race conditions:

const fs = require('fs');

fs.open('foo.txt', 'r', function (err, fd) {
  // ...
});

Using fs.existsSync:

if (fs.existsSync('foo.txt')) {
  // ...
}

Using fs.stat:

fs.stat('foo.txt', function(err, stat) {
  if (err == null) {
    console.log('File exists');
  } else if (err.code === 'ENOENT') {
    // file does not exist
    fs.writeFile('log.txt', 'Some log\n');
  } else {
    console.log('Some other error: ', err.code);
  }
});

---

Deprecated:

fs.exists is deprecated.

Using path.exists:

const path = require('path');

path.exists('foo.txt', function(exists) { 
  if (exists) { 
    // ...
  } 
});

Using path.existsSync:

if (path.existsSync('foo.txt')) { 
  // ...
}