Node.js pretty basic but sneaky error

Question

Gooday guys, I've a problem with Node.js. I have recently started to learn it from w3schools. But when I copied this piece of code, than the following exception occurs:

TypeError: First argument must be a string or Buffer

I have index.html file which looks pretty basic. It shouldn't be a mess for the code.

var http = require('http');
var fs = require('fs');
http.createServer(function (req, res) {
  fs.readFile('index.html', function(err, data) {
    res.writeHead(200, {'Content-Type': 'text/html'});
    res.write(data);
    res.end();
  });
}).listen(8080);

Answer 1

Don't ignore errors! ( it makes everything worse)

fs.readFile('index.html', function(err, data) {

This either passes data and err will be null , or if an error occurs data will be null and err is an Error . When the later happens you ignore it and do

res.write(data);

which won't work as data is null and you can't send null to the client ( only Buffers or Strings as said in the error). So what to do? Well add an error handler:

fs.readFile('index.html', function(err, data) {
 if(err)
   return res.write(err.message);

 res.writeHead(200, {'Content-Type': 'text/html'});
 res.write(data);
 res.end();
});

So now you will probably get the real error which is

File not found

So you may check if youve got an index.html file.

Answer 2

It's happening mostly because of either res.write() or res.end() either one of it accepts string as its first argument try using res.send(data) will work fine. Have a good day. Happy Learning NodeJS