Web browsers making request to server twice-CodePudding

I wrote a simple nodejs code to make request to a server and noticed that on web browser the request is made twice but once when I use CURL.

const http = require('http');

// The server should respind to all request with a string "Hello World"
let count = 0;
const server = http.createServer((req, res) => {
    res.end(`${  count} Hello World \n`);
})

// Start the server and have it listen on port 3000

server.listen(3000, () => console.log('The server is is listening on port 3000'));

Can you explain why?

CodePudding user response：

My guess is a preflight request to OPTIONS. You could look at the network tab in the Chrome console to see. You probably only want to respond to the GET request.