Cant use parseInt() in LocalHost NodeJS - Body Parser - node.js

Question

im actully new in node js so i got this error while using parseInt or Number() in my server
code :
const express = require("express");
const app = express();
const bodyParser = require("body-parser");
app.use(bodyParser.urlencoded({ extended: true }));
app.get("/bmicalculator", function(req, res) {
res.sendfile(__dirname + "/index.html");
});
app.post("/bmicalculator", function(req, res) {
var nm1 = parseInt(req.body.num1); // <-- here the error
var nm2 = parseInt(req.body.num2); // <-- here the error
var result = nm1 + nm2 * nm2;
res.send(result);
});
app.listen(3000, function() {
console.log("server started");
});
here the error from Browser & Terminal :
RangeError [ERR_HTTP_INVALID_STATUS_CODE]: Invalid status code: 29636
at ServerResponse.writeHead (_http_server.js:248:11)
at ServerResponse._implicitHeader (_http_server.js:239:8)
at ServerResponse.end (_http_outgoing.js:763:10)
at ServerResponse.send (C:\Users\Amir\Desktop\Calculator\node_modules\express\lib\response.js:221:10)
at C:\Users\Amir\Desktop\Calculator\calculator.js:16:9
at Layer.handle [as handle_request] (C:\Users\Amir\Desktop\Calculator\node_modules\express\lib\router\layer.js:95:5)
at next (C:\Users\Amir\Desktop\Calculator\node_modules\express\lib\router\route.js:137:13)
at Route.dispatch (C:\Users\Amir\Desktop\Calculator\node_modules\express\lib\router\route.js:112:3)
at Layer.handle [as handle_request] (C:\Users\Amir\Desktop\Calculator\node_modules\express\lib\router\layer.js:95:5)
at C:\Users\Amir\Desktop\Calculator\node_modules\express\lib\router\index.js:281:22

Answer 1

This error seems to be caused by the method res.send. In old version of Express (v3),
the first argument used to be http status code but in your case, it's a big number (invalid http status code), hence the error is thrown.
in order to fix this, you can do either
upgrade to a newer version of express.
do this res.send(200, result) instead.
See the Express v3 docs here for reference: https://expressjs.com/en/3x/api.html#res.send
res.send([body|status], [body])
Send a response.
res.send(Buffer.from('whoop'))
res.send({ some: 'json' })
res.send('<p>some html</p>')
res.send(404, 'Sorry, we cannot find that!')
res.send(500, { error: 'something blew up' })
res.send(200)
You can see your case is same as the last example but your first argument is a big number 29636, which is invalid status code.

Answer 2

Add:
app.use(bodyParser.json());
And change the reponse to:
res.send(200, result);