Wrong node

fs.js

var fs = require('fs');

var random = (~~(Math.random() * 1e9)).toString(2);


fs.writeFile('./random.txt', random, function(err){
  if(err) console.error(err);
  else console.log('file has been written');
});

fs.readFile('./random.txt','utf8', function(err, file){
  if(err) console.error(err);
  else
  console.log(file);
});