fs.writefile is making POST request loop infinitly within my express app - node.js

Question

I have this current server code:
const express = require("express")
const fs = require("fs")
const router = express.Router()
const path = require("path")
const todos = JSON.parse(fs.readFileSync(path.join(__dirname, "../db", "todolist.json"), "utf8"))
router.get("/", async (req, res) => {
res.send(todos)
})
router.post("/new", async (req, res) => {
const { title, description } = req.body
const todoItem = {
id: "3",
title,
description
}
todos.todos.push(todoItem)
const data = JSON.stringify(todos, null, 2)
fs.writeFile(path.join(__dirname, "../db", "todolist.json"), data, () => {})
res.status(201).json(todoItem)
})
client:
console.log("Hello world!")
const somedata = {
title: "A new boy",
description: "Recieved from the client"
}
const main = async () => {
const response1 = await fetch("http://localhost:3000/todo", {
method: "GET",
})
const data1 = await response1.json()
const response2 = await fetch("http://localhost:3000/todo/new", {
method: "POST",
body: JSON.stringify(somedata),
headers: {
'Content-Type': 'application/json',
"Accept": "application/json"
}
})
const data2 = await response2.json()
return { data1, data2 }
}
main().then(data => console.log(data))
When I make a /POST request to create a new entity the browser just loops the request over and over until I manually have to quit the server. This does not happen if I use postman for some reason. Does anybody see any obvious error here with how the writeFile-method is used and why it continuously reloads the browser to keep pushing POST requests?
Thanks! :)

Answer 1

i had the same problem! And it took me about 1 hour to understand what my Problem is:
If you use "live server extension", the server will restart everytime, when you write, change or delete a file in the project folder!
So, if your node-app wirte a file, the live-server will restart and the app writes the file again! => loop
In my case, i write a pdf-file. All i had to do, is to tell the live server extension to ignore pdf files:
So i just add to "settings.json":
"liveServer.settings.ignoreFiles":["**/*.pdf"]

Answer 2

fs.writeFile is asynchronous function. So, to send a response after file written you must do it in the callback. And of course, don't forget about error checking. I.e.
router.post("/new", async (req, res) => {
const { title, description } = req.body
const todoItem = {
id: "3",
title,
description
}
todos.todos.push(todoItem)
const data = JSON.stringify(todos, null, 2)
fs.writeFile(path.join(__dirname, "../db", "todolist.json"), data, (err) => {
if(err) {
throw err;
}
res.status(201).json(todoItem)
})
})
Or you can use fs.writeFileSync as Muhammad mentioned earlier.

Answer 3

I think I found the problem. It seemed that the live server extension was messing things up when I had the client and server on separate ports, making the browser refresh for every request made somehow. I switched back to them sharing port, which then makes it work. I have to find a good way of separating them on a later basis without this bug happening, but that is for another time.
Thanks for your help :)

Answer 4

I share my working sample.body-parser dependency is need to get body in post request.Please don't change the order in server.js.Check and let me know.
and also check once whether your client code is in in loop.
My server.js
const express = require("express")
const fs = require("fs")
const router = express.Router()
const path = require("path")
const app = express();
const bodyParser = require("body-parser")
const todos = JSON.parse(fs.readFileSync(path.join(__dirname, "../db", "todolist.json"), "utf8"))
app.use(bodyParser.json());
app.use("/",router)
router.get("/todo", async (req, res) => {
res.send(todos)
})
router.post("/todo/new", async (req, res) => {
const { title, description } = req.body
const todoItem = {
id: "3",
title,
description
}
todos.todos.push(todoItem)
const data = JSON.stringify(todos, null, 2)
fs.writeFile(path.join(__dirname, "../db", "todolist.json"), data, () => {})
res.status(201).json(todoItem)
});
app.listen(3000, () => {
console.log(`Server running in Port`);
});
todolist.json
{
"todos": []
}

Answer 5

I think you should use fs.writeFileSync() or write some code in its callback