I'm assuming you're making a POST request with a JSON payload. First, you want to make sure your payload is formatted JSON correctly, use: http://pro.jsonlint.com/

Secondly, you can send the payload using JSON.stringify and you will want to set the contentType:

data: JSON.stringify(data), contentType: "application/json; charset=utf-8"

If you run this and look at your network tab in Dev Tools in Chrome, it will error out, but you will at least see the payload formatted to send to the server: http://prntscr.com/f8hf6s

var data = [{
    "key": "myKey",
    "keyName": "myKeyName",
    "value": "value",
    "valueName": "valueName"
  },
  {
    "key": "mySecondKey",
    "keyName": "mySecondKeyName",
    "value": "secondValue",
    "valueName": "secondValueName"
  }
];

var url = "http://swapi.co/api/";

$.ajax({
  type: "POST",
  url: url,
  data: JSON.stringify(data),
  contentType: "application/json; charset=utf-8",
  dataType: "json",
  error: function() {
    alert("Error");
  },
  success: function() {
    alert("OK");
  }
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

Try this one:

var a = {};
a['test'] = 1;
a['test2'] = 2;

// or


var a = {};
a.test = 1;
a.test2 = 2;

// or


var a = {
    test : 1,
    test2 : 2
};

$.ajax({
  url: baseUrl+"chat.php",
  data: a,
  type: 'post',
  success: function(data) {
    alert(data);
  }
});

You may then access the data in your PHP script like this:

$_POST['test'];
$_POST['test2'];

I generally use $.ajax for this purpose but since you have asked not to use jquery, so in that case you need to make XHR Request to the endpoint specified in you node application.

Client Side

var xmlhttp;

if (window.XMLHttpRequest) {

    // code for IE7+, Firefox, Chrome, Opera, Safari
    xmlhttp = new XMLHttpRequest();
}

else {
    // code for IE6, IE5
    xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}

xmlhttp.onreadystatechange = function() {
    if (xmlhttp.readyState == XMLHttpRequest.DONE ) {
       if(xmlhttp.status == 200){
           console.log('request successfull : ', xmlhttp.responseText);
       }
       else if(xmlhttp.status == 400) {
          alert('There was an error 400')
       }
       else {
           alert('something else other than 200 was returned')
       }
    }
}

xmlhttp.open("post", "~/process_post", true);
xmlhttp.send(JSON.stringify(..........)); //your custom data

Server Side Node

app.post('/process_post', urlencodedParser, function (req, res) { 
    console.log("Got request: " + res.body);
});

Just looking for some another question already asked on Stackoverflow, I find this useful for you.

That's not how POST request works. Read more about Ajax, but for now, that's how you should do it.

var songlist = ['song1', 'song2', 'song3'];

var sendData = function() {
  $.post('test.php', {
    data: songlist
  }, function(response) {
    console.log(response);
  });
}
sendData();

// test.php
<?php
$songData = $_POST['data'];
print_r($songData);
?>

Try this one:

var a = {};
a['test'] = 1;
a['test2'] = 2;

// or


var a = {};
a.test = 1;
a.test2 = 2;

// or


var a = {
    test : 1,
    test2 : 2
};

$.ajax({
  url: baseUrl+"chat.php",
  data: a,
  type: 'post',
  success: function(data) {
    alert(data);
  }
});

You may then access the data in your PHP script like this:

$_POST['test'];
$_POST['test2'];

This issue popped up for me as well, and I solved it with new FormData().

Having an array:

const product_id_list = ['pid1234', 'pid1235']

const bodyFormData = new FormData();

product_id_list.forEach((item) => {
    bodyFormData.append('product_id_list[]', item);
});

axios.post('https://test.com/api/get_product', bodyFormData)

Doing it this way sent it the request as application/x-www-form-urlencoded, and the proper data in the body.

If you want to pass a JavaScript object/hash (ie. an associative array in PHP) then you would do:

$.post('/url/to/page', {'key1': 'value', 'key2': 'value'});

If you wanna pass an actual array (ie. an indexed array in PHP) then you can do:

$.post('/url/to/page', {'someKeyName': ['value','value']});

If you want to pass a JavaScript array then you can do:

$.post('/url/to/page', {'someKeyName': variableName});

Be sure to stringify before sending. I leaned on the libraries too much and thought they would encode properly based on the contentType I was posting, but they do not seem to.

Works:

$.ajax({
    url: _saveAllDevicesUrl
,   type: 'POST'
,   contentType: 'application/json'
,   data: JSON.stringify(postData) //stringify is important
,   success: _madeSave.bind(this)
});

I prefer this method to using a plugin like $.toJSON, although that does accomplish the same thing.

In JavaScript / JSON arrays are 0 based indexed data structures. What you are using here is more like a Map:

var jsonArray = [];
jsonArray["company_name"]=company_name ;

In JavaScript you cannot use arrays like this (well you can, but it is probably not what you want). For a data structure like a map that maps strings to objects rather then an index to objects, just use an object.

Or in short: Use var jsonArray = {}; rather than var jsonArray = []; The {} will create an object that you can assign properties to like you did. And JSON.stringify will correctly translate this into a JSON string like this:

{ "property": value, "otherProperty", otherValue }

You can do JSON.stringify(). This will convert your array into a string, which can be passed across the network via GET or POST. In the node server, you can parse this string and get the array using JSON.parse. Adding a working Example below

var Coordinates = [
      {lat: 37.772, lng: -122.214},
      {lat: 21.291, lng: -157.821},
      {lat: -18.142, lng: 178.431},
      {lat: -27.467, lng: 153.027}
                              ];

var a = JSON.stringify(Coordinates)
console.log('Coordinates string: ', a)

var parsed = JSON.parse(a)
console.log('Parsed Coordinates: ', parsed)

Ok, from your question I understand that you want to manipulate the POST Body like a json array then use qs library by making extended true

app.use(bodyParser.urlencoded({ extended: true }));

You javascipt object properties do not have indexers, so you need to use the ajax contentType: "application/json" option and stringify the object

var myArray = [{"id": 1, "name", "John"},{"id": 2, "name", "Joe"},{"id": 3, "name", "Bill"}] 

$.ajax({
  type: 'post',
  url: '@Url.Action("Update", "MyController")', // don't hardcode your url's!
  contentType: "application/json; charset=utf-8",
  data: JSON.stringify({ people: myArray }),
  success: function (data) {
    ....
  }
})

Side note. The following object would post back

var myArray = { people[0].id: 1, people[0].name: "John", people[1].id: 2, people[1].name: "Joe" }

using

$.post('@Url.Action("Update", "MyController")', myArray, function() {`