Go to CodeSandbox.io and then press new + and then press Node.js using DevBox then you can just run the start task which runs the app using modemon and to create an app using HTTP then use the http one and if you want to use express then use this

var express=require(‘express’)
var app=express()
app.use(‘/‘, function(req, res, next){res.send(‘hello world’);next()})
app.listen(3000, function(){})