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Can't get all JSON to show up

It will always display the "cretetion" associated link JSON as the others are overwritten. So I tried incrementing to get all of them, but it didn't work. I don't know what I am doing wrong.
var users = ["ESL_SC2", "OgamingSC2", "cretetion"];
function loadXMLDoc() {
var xmlhttp = new XMLHttpRequest();
for (var i = 0; i < users.length ; i++) {
var url = "https://wind-bow.glitch.me/twitch-api/streams/" + users[i];
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == XMLHttpRequest.DONE ) {
if (xmlhttp.status == 200) {
document.getElementById('online-id').innerHTML += (xmlhttp.responseText + "<br />");
}else if (xmlhttp.status == 400) {
console.log('There was an error 400');
}else {
console.log('Something else other than 200 was returned.');
}
}
}
xmlhttp.open("GET", url, true);
xmlhttp.send();
}
}
var onlineButton = document.getElementById('online-button-id');
onlineButton.addEventListener('click', loadXMLDoc, false);

I've fixed your code here:
https://plnkr.co/edit/VbkKc9QuVALAYLpujSdo?p=preview
First, the callback xmlhttp.onreadystatechange is overwritten every iteration of the loop so only the last element will be handled.
you should create and manage the XMLHttp object inside the loop, one for each element of your user array.
Secondy and most important you must wrap xmlhttp.onreadystatechange inside an Immediate invoked function otherwise each callback will use the last xmlhttp object then you will be getting the last result all the time, as you were saying above.
for (var i = 0; i < users.length ; i++) {
var xmlhttp = new XMLHttpRequest();
var url = "https://wind-bow.glitch.me/twitch-api/streams/" + users[i];
(function(xmlhttp){
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == XMLHttpRequest.DONE ) {
if (xmlhttp.status == 200) {
document.getElementById('online-id').innerHTML += (xmlhttp.responseText + "<br/><br/>");
}else if (xmlhttp.status == 400) {
console.log('There was an error 400');
}else {
console.log('Something else other than 200 was returned.');
}
}
}
})(xmlhttp)
xmlhttp.open("GET", url, true);
xmlhttp.send();
}

Try creating a new XMLHttpRequest for each iteration of the loop instead of re-using the same one. i.e.
function loadXMLDoc() {
for (var i = 0; i < users.length ; i++) {
var xmlhttp = new XMLHttpRequest();
...

XMLHTTP Request post data hangs

I'm trying to create an AJAX call with the post method, and can't get it to work right. The script hangs at the processing stage (readyState does not go on to 4).
I'd appreciate it if someone could enlighten me on the issue here. I've looked at a couple of tutorials, and it seems that my code -should- work.
function newRequestPost(url, post, threadid, cfunc) {
if(window.XMLHttpRequest) {
xmlhttp = new XMLHttpRequest();
} else {
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
var params = "post="+post+"&threadid="+threadid;
xmlhttp.onreadystatechange = cfunc;
xmlhttp.open("POST", url, true);
xmlhttp.setRequestHeader("Content-type","application/x-www-form-urlencoded");
xmlhttp.send(params);
}
function openModalPreview(threadid) {
var post = document.getElementById("post_txt").value;
newRequestPost("url", post, threadid, function() {
if(xmlhttp.readyState == 1) {
document.getElementById("that_which_lies_in_the_modal").innerHTML = "Loading...";
}
if(xmlhttp.readyState == 2) {
document.getElementById("that_which_lies_in_the_modal").innerHTML = "Received";
}
if(xmlhttp.readyState == 3) {
document.getElementById("that_which_lies_in_the_modal").innerHTML = "Processing...";
}
if(xmlhttp.readyState == 4 && xmlhttp.status == 200) {
document.getElementById("that_which_lies_in_the_modal").innerHTML = xmlhttp.responseText;
}
});
}

get data from XMLHttprequest

I want to get data in json format.
I have typed this code but it doesn't return anything.
where is the problem in my code?!!
<script language="JavaScript">
var xmlhttp = new XMLHttpRequest();
var url = "http://codeforces.com/api/contest.list?gym=true";
xmlhttp.onreadystatechange = myfunction;
xmlhttp.open("GET", url, true);
xmlhttp.send(null);
function myfunction() {
if (XMLHttp.readyState == 0) {
window.alert("Uninitialized");
}
if (XMLHttp.readyState == 1) {
window.alert("loading");
}
if (XMLHttp.readyState == 2) {
window.alert("loaded");
}
if (XMLHttp.readyState == 3) {
window.alert("waiting");
}
if (XMLHttp.readyState == 4) {
window.alert("completed");
var y = JSON.parse(xmlhttp.responseText);
document.getElementById("id01").innerHTML =y[1].id;
}
}
</script>
in the html code, i have a div with id = "id01"

remember that javascript is case sensitive.
edit it to:
var xmlhttp = new XMLHttpRequest();
var url = "http://codeforces.com/api/contest.list?gym=true";
xmlhttp.onreadystatechange = myfunction;
xmlhttp.open("GET", url, true);
xmlhttp.send(null);
function myfunction() {
if (xmlhttp.readyState == 0) {
window.alert("Uninitialized");
}
if (xmlhttp.readyState == 1) {
window.alert("loading");
}
if (xmlhttp.readyState == 2) {
window.alert("loaded");
}
if (xmlhttp.readyState == 3) {
window.alert("waiting");
}
if (xmlhttp.readyState == 4) {
window.alert("completed");
var y = JSON.parse(xmlhttp.responseText);
document.getElementById("id01").innerHTML =y[1].id;
}
}

try this:
xmlhttp.onload = function() {
if (xmlhttp.status >= 200 && xmlhttp.status < 400) {
// Success!
var data = JSON.parse(xmlhttp.responseText);
} else {
// We reached our target server, but it returned an error
}
};
disclaimer: i took this code from http://youmightnotneedjquery.com/#json

Just use fetch. It is the modern XMLHttpRequest.
const url = "http://codeforces.com/api/contest.list?gym=true";
fetch(url)
.then(
response => response.json() // .text(), etc.
// same as function(response) {return response.json();}
).then(
jsonString => {
const json = JSON.parse(jsonString);
document.getElementById("id01").innerHTML = json[1].id;
}
);
More Info:
Mozilla Documentation
Can I Use (75% Aug 2017)
Matt Walsh Tutorial

javascript poll php script every 5 seconds

How do I check a value in a php script for change using javascript?
I would like to do something like:
<script type="text/javascript"><!--
var innitialID = get_file_contents(lastPresentID.php); //get_file_contents(lastPresentID.php);
function myTimeout() {
var freshestID = get_file_contents(lastPresentID.php);
if(freshestID != innitialID) {
location.reload();
}
setTimeout(myTimeout, 5000);
}
window.onload = myTimeout;
</script>
the php script generates a single integer which is the last ID of a table.
Thanks!

<script type="text/javascript">
window.onload = doAjax(true);
setInterval(doAjax, 5000);
var initialID = -1, freshestID;
function doAjax(initial) {
var xmlhttp;
if (window.XMLHttpRequest) {
xmlhttp = new XMLHttpRequest(); // code for IE7+, Firefox, Chrome, Opera, Safari
} else {
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP"); // code for IE6, IE5
}
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200){
if(initial) {
initialID = xmlhttp.responseText;
} else {
freshestID = xmlhttp.responseText;
if (initialID != freshestID)
location.reload();
}
}
}
xmlhttp.open("GET", "lastPresentID.php", true);
xmlhttp.send();
}
</script>
Here we go, updated with ajax calls in there. First sets the initialId variable, then the interval code runs every 5 seconds and update the freshestId variable, and does the comparision.
EDIT: Code is now not duplicated.

The code below on load will assigns oldVal. Then using setInterval will update newVal every 5 secodns and check if newVal != oldVal.
It gets the values from lastPresentID.php using AJAX.
var oldVal = 0;
var newVal = 0;
function loadXMLDoc(old) {
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 == 4 ) {
if(xmlhttp.status == 200){
if(old)
{
oldVal = xmlhttp.responseText;
}
else
{
newVal = xmlhttp.responseText;
if(newVal != oldVal)
alert("test");
}
}
else if(xmlhttp.status == 400) {
alert('There was an error 400')
}
else {
alert(xmlhttp.status)
}
}
}
xmlhttp.open("GET", "lastPresentID.php", true);
xmlhttp.send();
}
function timeout() {
loadXMLDoc(false);
}
loadXMLDoc(true);
setInterval(timeout, 5000);

XMLHttpRequest status is 0 why?

Here is my code:
var xmlhttp;
function HttpObject(str)
{
//alert("iam in process request");
if (window.XMLHttpRequest)
{
xmlhttp = new XMLHttpRequest();
alert ("xmlhttp");
}
else if(window.ActiveXObject)
{
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
alert ("ms.xmlhttp");
}
else
{
XmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
}
alert ("rdystate: " + xmlhttp.readyState);
alert ("status: " + xmlhttp.status);
alert ("Text: " + xmlhttp.statusText);
xmlhttp.onreadystatechange = processRequest();
xmlhttp.open("POST",'/CountryTest.do',true);
xmlhttp.send(null);
}
function processRequest()
{
if (xmlhttp.readyState === 0) {
alert("u r in 0 :: The request is not initialized ");
}
var target = document.getElementById("curlist");
var res = xmlhttp.responseText;
alert(res);
if (xmlhttp.readyState === 4 && xmlhttp.status === 200)
{
alert("in readystate");
}
else
{
alert("error in readystate");
}
}
It always displaying status 0
curlist is id of my country state prog
can any one say me where is problem?
/CountryTest.do is the url pattern of the servlet.

xmlhttp.onreadystatechange = processRequest();
You just called processRequest immediately, and assigned its return value to onreadystatechange.
You want to assign the function itself, without calling it.

xmlhttp.onreadystatechange = function()
{
if (xmlhttp.readyState=='4')
{
alert(xmlhttp.responseText);
}
}