Unable to Connect to Backend - react-native

Question

Hello i am Trying to connect React-Native with Node.js using Fetch Api i tried many solutions i tried putting my IP address,localhost and 10.0.2.2 but nothing works i dont get any response back but when i change my code a little bit it gives me network failed request error.
React-Native Code:
//Sending Request to Node.js using Fetch API
await fetch("http://10.0.2.2:3000/studentSignup", {
//Setting Method
method:"POST",
//Setting Headers
headers:{
//Setting Content-Type
"Content-Type" : "application/json"
},
//Stringifying the email and password and storing it into body
body:JSON.stringify({
name,
gmail,
password,
retype
})
}).then(res=>{
console.log(res);
}).catch(err=>{
console.log(err);
});
Node.js:
const express = require("express");
const app = express();
app.use("/studentSignup", (req,res,next)=>{
console.log("ok");
});
app.listen(3000);

Answer 1

lots of Mistakes
Full source code
var express = require('express')
var cors = require('cors')
var app = express()
var bodyParser = require('body-parser')
// create application/json parser
var jsonParser = bodyParser.json()
// create application/x-www-form-urlencoded parser
var urlencodedParser = bodyParser.urlencoded({ extended: false })
app.use(jsonParser)
app.use(urlencodedParser)
app.use(cors())
app.post("/studentSignup", (req,res,next)=>{
console.log("ok");
});
app.listen(3000);
First of all, it's app.post not app.use
app.post("/studentSignup", (req,res,next)=>{
console.log("ok");
});
This might me due to cors
You can use this npm package to encounter this error cors
install cors in server folder
npm i cors --save
Usage
var express = require('express')
var cors = require('cors')
var app = express()
app.use(cors())
app.post("/studentSignup", (req,res,next)=>{
console.log("ok");
});
app.listen(3000);
Use body parser to handle incoming data from frontend
install body-parser in server folder
npm i body-parser --save
Usage
var express = require('express')
var cors = require('cors')
var app = express()
var bodyParser = require('body-parser')
// create application/json parser
var jsonParser = bodyParser.json()
// create application/x-www-form-urlencoded parser
var urlencodedParser = bodyParser.urlencoded({ extended: false })
app.use(jsonParser)
app.use(urlencodedParser)
app.use(cors())
app.post("/studentSignup", (req,res,next)=>{
console.log("ok");
});
app.listen(3000);

Answer 2

So i was debugging and i thought that i have 2 ip's first one was Internet's ip and the second one was mine pc's ip and i was using internet's ip instead of my machine's ip so i changed the ip and that worked smoothly.