sending the value from javascript(client side) to express (server side)

Question

I create the HTML DOM in javascript that you see the below code. Now, I want send the value of input that I created in javascript to server side. My server that created with node.js and express framework. After sending the value to server side, I want to save this value in my json file. I know how to read and write json file, but my problem is sending this value. Here is my javascript code and express code. In javascript code I want send the inTask variable and in the server code I want to receive this value in app.post .

1.javascript code

let newTask = [];
function addInput() {
    document.getElementById("link").style.display = "none";
    var input = document.createElement("input");
    input.type = "text";
    input.setAttribute("id", "inValue");
    document.getElementById("input").appendChild(input);
    var addBtn = document.createElement("button");
    var text = document.createTextNode("Add Task");
    addBtn.appendChild(text);
    addBtn.addEventListener("click", addTask);
    document.getElementById("input").appendChild(addBtn);
 }

 function addTask() {
     var inTask = document.getElementById("inValue").value;
     var xhttp = new XMLHttpRequest();
     xhttp.onreadystatechange = function() {
     if (this.readyState == 4 && this.status == 200) {
     document.getElementById("demo").innerHTML = this.responseText;
     }
    };
    xhttp.open("POST", "/login", true);
    xhttp.setRequestHeader("Content-type", "application/x-www-form-
       urlencoded");
    xhttp.send(document.getElementById("inValue").value);
     }

2. server.js:

 var express = require("express"); var bodyParser = require("body-parser"); var app = express(); var fs = require('fs'); app.use(express.static(__dirname + "/static")); app.use(bodyParser.json()); app.use(bodyParser.urlencoded({ extended:true })); app.get("/" , function (req, resp, next) { resp.sendFile(__dirname + "/static/index.html"); }) ; app.post("/login" , function (req, resp, next) { var jsonData = req.body.inValue; fs.writeFile("data.json", jsonData, function(err) { if(err) { return console.log(err); } }); res.json(jsonData); }); app.listen(3000); console.log("app running on port 3000"); 

Answer 1

You expect a json-Data in your server file, but you don't send a json-Object. Exchange xhttp.send(document.getElementById("inValue").value); with

xhttp.send(JSON.stringify( { inValue: document.getElementById("inValue").value });