Node: fs.readFileSync doesn't work in windows environment

[saeidalidadi]

I have used fs.readFile and the Sync method fs.readFileSync the same file as below :
first fs.readFile give the expect result:

var fs = require('fs');
var path = require('path');

//Normalizing the path for windows environment
var normalPath = path.normalize( __dirname + '/test.txt');

//Reading the test.txt file in Async mode
fs.readFile( normalPath, function(err, data) {
    console.log( data.toString() );
});

and fs.readFileSync that runs with error:

var fs = require('fs');
var path = require('path');

//Normalizing the path for windows environment
var normalPath = path.normalize( __dirname + '/test.txt');

//Reading the test.txt file in Async mode
fs.readFileSync( normalPath, function(err, data) {

    console.log( data.toString() );

});

This is the error that I encountered with:

fs.js:40
  throw new TypeError('Expected options to be either an object or a string, ' +
  ^

TypeError: Expected options to be either an object or a string, but got function
 instead
    at throwOptionsError (fs.js:40:9)
    at Object.fs.readFileSync (fs.js:423:5)
    at Object.<anonymous> (C:\Users\Arash\Desktop\learnyounode\program.js:8:4)
    at Module._compile (module.js:413:34)
    at Object.Module._extensions..js (module.js:422:10)
    at Module.load (module.js:357:32)
    at Function.Module._load (module.js:314:12)
    at Function.Module.runMain (module.js:447:10)
    at startup (node.js:140:18)
    at node.js:1001:3

[ericmdantas]

readFileSync will return the data you're looking for, so instead of:

fs.readFileSync( normalPath, function(err, data) {
    console.log( data.toString() );
});

Just do:

var data = fs.readFileSync( normalPath );

[targos]

@ericmdantas is right. The synchronous methods of fs return the result (or throw if there is an error). They do not take a callback argument.

[brutalcrozt]

notice that i do like so:

var fs = require('fs');

fs.readFile(validFile, 'utf8', (err, data)=> {
  if (err) {
    throw err;
  }
  console.log('async readFile');
  console.log(data);
});


fs.readFileSync(validFile, 'utf8', (err, data)=> {
  if (err) {
    throw err;
  }
  console.log('sync readFile');
  console.log(data);
});

The result is the sync version not even logging, like not executed.
IDK if it possible to reproduce it online. I am using v4.2.6

[ericmdantas]

@brutalcrozt that's because there's no callback when you use readFileSync, you should do:

try {
  var data = fs.readFileSync(validFile, 'utf8');
  console.log('sync readFile');
  console.log(data);
}
catch (e) {
  console.log(e);
}

[brutalcrozt]

Thanks @ericmdantas that is my bad, stupid while looking the documentation.

[ericmdantas]

No worries :smile: