Unexpected JavaScript output on console

Question

I was trying to run a piece of Node.js code. This is the code:

var fs = require("fs");
fs.readFile('input.txt', function(err, data) {
  if (err) return console.error(err);
  console.log(data.toString());
});

console.log("Program Ended");
var http = require("http");
http.createServer(function(request, response) {

  // Send the HTTP header 
  // HTTP Status: 200 : OK
  // Content Type: text/plain
  response.writeHead(200, {
    'Content-Type': 'text/plain'
  });

  // Send the response body as "Hello World"
  response.end('Hello World\n');
}).listen(8081);

// Console will print the message
console.log('Server running at http://127.0.0.1:8081/');

When I ran it on the Linux terminal on my laptop, the content of the input.txt file appeared after the "Server running" command in the last line. Ideally, first the readfile command output should have been there, shouldn't it?

The output coming out is as follows:

Program ended

Server running at....

(content of the txt file)

Why should it be there first, considering fs.readFile is an asynchronous method, isn't the order correct? — Teemu
– Teemu, Commented Dec 27, 2017 at 12:55

Christopher Lebbano Chris · Accepted Answer · 2017-12-27 12:57:20Z

5

fs.readFile() is an async method, so it may or may not finish before the rest of your code, it's just done when it's done.

check out readFileSync()

https://nodejs.org/api/fs.html#fs_fs_readfilesync_path_options

answered Dec 27, 2017 at 12:57

Christopher Lebbano Chris

661 bronze badge

Sign up to request clarification or add additional context in comments.

1 Comment

WhatsThePoint Over a year ago

While this link may assist in your answer to the question, you can improve this answer by taking vital parts of the link and putting it into your answer, this makes sure your answer is still an answer if the link gets changed or removed :)

Collectives™ on Stack Overflow

Unexpected JavaScript output on console

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related