Node.js check if file exists

Question

How do i check the existence of a file?

In the documentation for the module fs there\'s a description of the method fs.exists(path, cal

Answer 1

vannilla Nodejs callback

function fileExists(path, cb){
  return fs.access(path, fs.constants.F_OK,(er, result)=> cb(!err && result)) //F_OK checks if file is visible, is default does no need to be specified.
}

the docs say you should use access() as a replacement for deprecated exists()

Nodejs with build in promise (node 7+)

function fileExists(path, cb){
  return new Promise((accept,deny) => 
    fs.access(path, fs.constants.F_OK,(er, result)=> cb(!err && result))
  );
}

Popular javascript framework

fs-extra

var fs = require('fs-extra')
await fs.pathExists(filepath)

As you see much simpler. And the advantage over promisify is that you have complete typings with this package (complete intellisense/typescript)! Most of the cases you will have already included this library because (+-10.000) other libraries depend on it.

Answer 2

Modern async/await way ( Node 12.8.x )

const fileExists = async path => !!(await fs.promises.stat(path).catch(e => false));

const main = async () => {
    console.log(await fileExists('/path/myfile.txt'));
}

main();

We need to use fs.stat() or fs.access() because fs.exists(path, callback) now is deprecated

Another good way is fs-extra

Answer 3

After a bit of experimentation, I found the following example using fs.stat to be a good way to asynchronously check whether a file exists. It also checks that your "file" is "really-is-a-file" (and not a directory).

This method uses Promises, assuming that you are working with an asynchronous codebase:

const fileExists = path => {
  return new Promise((resolve, reject) => {
    try {
      fs.stat(path, (error, file) => {
        if (!error && file.isFile()) {
          return resolve(true);
        }

        if (error && error.code === 'ENOENT') {
          return resolve(false);
        }
      });
    } catch (err) {
      reject(err);
    }
  });
};

If the file does not exist, the promise still resolves, albeit false. If the file does exist, and it is a directory, then is resolves true. Any errors attempting to read the file will reject the promise the error itself.

Answer 4

fs.exists has been deprecated since 1.0.0. You can use fs.stat instead of that.

var fs = require('fs');
fs.stat(path, (err, stats) => {
if ( !stats.isFile(filename) ) { // do this 
}  
else { // do this 
}});

Here is the link for the documentation fs.stats

Answer 5

in old days before sit down I always check if chair is there then I sit else I have an alternative plan like sit on a coach. Now node.js site suggest just go (no needs to check) and the answer looks like this:

    fs.readFile( '/foo.txt', function( err, data )
    {
      if(err) 
      {
        if( err.code === 'ENOENT' )
        {
            console.log( 'File Doesn\'t Exist' );
            return;
        }
        if( err.code === 'EACCES' )
        {
            console.log( 'No Permission' );
            return;
        }       
        console.log( 'Unknown Error' );
        return;
      }
      console.log( data );
    } );

code taken from http://fredkschott.com/post/2014/03/understanding-error-first-callbacks-in-node-js/ from March 2014, and slightly modified to fit computer. It checks for permission as well - remove permission for to test chmod a-r foo.txt