create a web server for local html using node

I’m tring to create a simple web server to run my local html file, and now I can get a server running on localhost using code below

var http = require('http');
var fs = require('fs');
var index = fs.readFileSync('index.html', 'utf8');

http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'html'});
  res.end(index);
}).listen(3000);

But there is a problem that every time I changed my html file, the web page on localhost is still the old one, I need to restart the server to make the changes visible.

I want to improve that and I tried to use koa or express, like code below

const express = require("express");
const app = express();

app.listen(3000, () => {
  console.log("Application started and Listening on port 3000");
});

app.get("/", (req, res) => {
  res.sendFile("test.html");
});

And I found that express can serve real-time html files, I don’t need to restart serve when files change.

How can I use http moudle to achieve that?

Answer

Currently you read the file when the program starts up. Then each time you get a request you serve up the data from the variable.

Move that code inside the callback function that runs when you get a request, then it will be updated each time a request comes in.

http.createServer(function (req, res) {
  var index = fs.readFileSync('index.html', 'utf8');
  res.writeHead(200, {'Content-Type': 'html'});
  res.end(index);
}).listen(3000);

You could avoid reading the file on each request by having the variable outside the function (as in your original code) and watching the file for changes (and updating the variable in response).

That said, using Express and its static module will provide benefits with caching and I’d recommend it over rolling your own.