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Send POST data using XMLHttpRequest


Question

I'd like to send some data using an XMLHttpRequest in JavaScript.

Say I have the following form in HTML:

<form name="inputform" action="somewhere" method="post">
  <input type="hidden" value="person" name="user">
  <input type="hidden" value="password" name="pwd">
  <input type="hidden" value="place" name="organization">
  <input type="hidden" value="key" name="requiredkey">
</form>

How can I write the equivalent using an XMLHttpRequest in JavaScript?

2020/07/21
1
540
7/21/2020 6:50:07 PM

Accepted Answer

The code below demonstrates on how to do this.

var http = new XMLHttpRequest();
var url = 'get_data.php';
var params = 'orem=ipsum&name=binny';
http.open('POST', url, true);

//Send the proper header information along with the request
http.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');

http.onreadystatechange = function() {//Call a function when the state changes.
    if(http.readyState == 4 && http.status == 200) {
        alert(http.responseText);
    }
}
http.send(params);
2018/05/25
765
5/25/2018 6:34:02 AM


Use modern JavaScript!

I'd suggest looking into fetch. It is the ES5 equivalent and uses Promises. It is much more readable and easily customizable.

const url = "http://example.com";
fetch(url, {
    method : "POST",
    body: new FormData(document.getElementById("inputform")),
    // -- or --
    // body : JSON.stringify({
        // user : document.getElementById('user').value,
        // ...
    // })
}).then(
    response => response.text() // .json(), etc.
    // same as function(response) {return response.text();}
).then(
    html => console.log(html)
);

In Node.js, you'll need to import fetch using:

const fetch = require("node-fetch");

If you want to use it synchronously (doesn't work in top scope):

const json = await fetch(url, optionalOptions)
  .then(response => response.json()) // .text(), etc.
  .catch((e) => {});

More Info:

Mozilla Documentation

Can I Use (95% Mar 2020)

David Walsh Tutorial

2020/06/20

Minimal use of FormData to submit an AJAX request

<!DOCTYPE html>
<html>
<head>
<meta http-equiv="X-UA-Compatible" content="IE=Edge, chrome=1"/>
<script>
"use strict";
function submitForm(oFormElement)
{
  var xhr = new XMLHttpRequest();
  xhr.onload = function(){ alert (xhr.responseText); } // success case
  xhr.onerror = function(){ alert (xhr.responseText); } // failure case
  xhr.open (oFormElement.method, oFormElement.action, true);
  xhr.send (new FormData (oFormElement));
  return false;
}
</script>
</head>

<body>
<form method="post" action="somewhere" onsubmit="return submitForm(this);">
  <input type="hidden" value="person"   name="user" />
  <input type="hidden" value="password" name="pwd" />
  <input type="hidden" value="place"    name="organization" />
  <input type="hidden" value="key"      name="requiredkey" />
  <input type="submit" value="post request"/>
</form>
</body>
</html>

Remarks

  1. This does not fully answer the OP question because it requires the user to click in order to submit the request. But this may be useful to people searching for this kind of simple solution.

  2. This example is very simple and does not support the GET method. If you are interesting by more sophisticated examples, please have a look at the excellent MDN documentation. See also similar answer about XMLHttpRequest to Post HTML Form.

  3. Limitation of this solution: As pointed out by Justin Blank and Thomas Munk (see their comments), FormData is not supported by IE9 and lower, and default browser on Android 2.3.

2018/01/05

Here is a complete solution with application-json:

// Input values will be grabbed by ID
<input id="loginEmail" type="text" name="email" placeholder="Email">
<input id="loginPassword" type="password" name="password" placeholder="Password">

// return stops normal action and runs login()
<button onclick="return login()">Submit</button>

<script>
    function login() {
        // Form fields, see IDs above
        const params = {
            email: document.querySelector('#loginEmail').value,
            password: document.querySelector('#loginPassword').value
        }

        const http = new XMLHttpRequest()
        http.open('POST', '/login')
        http.setRequestHeader('Content-type', 'application/json')
        http.send(JSON.stringify(params)) // Make sure to stringify
        http.onload = function() {
            // Do whatever with response
            alert(http.responseText)
        }
    }
</script>

Ensure that your Backend API can parse JSON.

For example, in Express JS:

import bodyParser from 'body-parser'
app.use(bodyParser.json())
2018/04/17

NO PLUGINS NEEDED!

Select the below code and drag that into in BOOKMARK BAR (if you don't see it, enable from Browser Settings), then EDIT that link :

enter image description here

javascript:var my_params = prompt("Enter your parameters", "var1=aaaa&var2=bbbbb"); var Target_LINK = prompt("Enter destination", location.href); function post(path, params) { var xForm = document.createElement("form"); xForm.setAttribute("method", "post"); xForm.setAttribute("action", path); for (var key in params) { if (params.hasOwnProperty(key)) { var hiddenField = document.createElement("input"); hiddenField.setAttribute("name", key); hiddenField.setAttribute("value", params[key]); xForm.appendChild(hiddenField); } } var xhr = new XMLHttpRequest(); xhr.onload = function () { alert(xhr.responseText); }; xhr.open(xForm.method, xForm.action, true); xhr.send(new FormData(xForm)); return false; } parsed_params = {}; my_params.split("&").forEach(function (item) { var s = item.split("="), k = s[0], v = s[1]; parsed_params[k] = v; }); post(Target_LINK, parsed_params); void(0);

That's all! Now you can visit any website, and click that button in BOOKMARK BAR!


NOTE:

The above method sends data using XMLHttpRequest method, so, you have to be on the same domain while triggering the script. That's why I prefer sending data with a simulated FORM SUBMITTING, which can send the code to any domain - here is code for that:

 javascript:var my_params=prompt("Enter your parameters","var1=aaaa&var2=bbbbb"); var Target_LINK=prompt("Enter destination", location.href); function post(path, params) {   var xForm= document.createElement("form");   xForm.setAttribute("method", "post");   xForm.setAttribute("action", path); xForm.setAttribute("target", "_blank");   for(var key in params) {   if(params.hasOwnProperty(key)) {        var hiddenField = document.createElement("input");      hiddenField.setAttribute("name", key);      hiddenField.setAttribute("value", params[key]);         xForm.appendChild(hiddenField);     }   }   document.body.appendChild(xForm);  xForm.submit(); }   parsed_params={}; my_params.split("&").forEach(function(item) {var s = item.split("="), k=s[0], v=s[1]; parsed_params[k] = v;}); post(Target_LINK, parsed_params); void(0); 
2019/10/26

I have faced similar problem, using the same post and and this link I have resolved my issue.

 var http = new XMLHttpRequest();
 var url = "MY_URL.Com/login.aspx";
 var params = 'eid=' +userEmailId+'&amp;pwd='+userPwd

 http.open("POST", url, true);

 // Send the proper header information along with the request
 //http.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
 //http.setRequestHeader("Content-Length", params.length);// all browser wont support Refused to set unsafe header "Content-Length"
 //http.setRequestHeader("Connection", "close");//Refused to set unsafe header "Connection"

 // Call a function when the state 
 http.onreadystatechange = function() {
    if(http.readyState == 4 && http.status == 200) {
        alert(http.responseText);
    }
 }
 http.send(params);

This link has completed information.

2018/02/23

Source: https://stackoverflow.com/questions/9713058
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