Develop Reference

JS: HTML is not dynamically changing

I am building an web that allows user to like a post when they click a button. CreateLike function calls API and creates a like object however, I would like to have the number of likes updated right away without reloading. I built another API that returns the number of likes for a post. Function LikeCount should put the number of likes into the p tag. It works initially when I load the page however, the value does not change when I click the button even though I can see that the API is called. (After reloading the page the number changes as expected) What am I doing wrong?
I have this HTML:
<p class="like-count" id={{post.id}}></p>
<script>LikeCount({{post.id}});</script>
<button type="button" class="btn-like" onclick="CreateLike({{user.id}},{{post.id}})"></button>
with JS functions:
function CreateLike (userid,postid) {
xhr = new XMLHttpRequest();
var url = "{% url 'likes' %}";
var csrftoken = getCookie('csrftoken')
xhr.open("POST", url, true);
xhr.setRequestHeader("X-CSRFToken",'{{ csrf_token }}')
xhr.setRequestHeader("Content-type", "application/json");
xhr.onreadystatechange = function () {
if (xhr.readyState == 4 && xhr.status == 200) {
var json = JSON.parse(xhr.responseText);
console.log(json.email + ", " + json.name)
}
}
var data = JSON.stringify({csrfmiddlewaretoken:csrftoken,"user":userid,"post":postid});
xhr.send(data);
LikeCount(postid);
}
function LikeCount(postid) {
var xmlhttp = new XMLHttpRequest();
var url = "{% url 'likecount' id=112233 %}".replace("112233", postid);
xmlhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
var myArr = JSON.parse(this.responseText);
myFunction(myArr);
}
};
xmlhttp.open("GET", url, true);
xmlhttp.send();
function myFunction(arr) {
var out = arr.like_count;
document.getElementById(postid).innerHTML = out;
}
}
Like count API looks like this:
{
"like_count": 1
}

if(xhr.readyState === XMLHttpRequest.DONE) {
var status = xhr.status;
if (status === 0 || (status >= 200 && status < 400)) {
LikeCount(); //Put your get like count here
} else {
// Handle Errors
}
}
Call LikeCount only after receiving the response of your POST request. Right now you're immediately sending a GET request without ensuring if the previous POST request got completed.

Added
xhr.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 201) {
var myArr = JSON.parse(this.responseText);
LikeCount(myArr.post);
}
};
before
xhr.send(data);
and it fixed the issue.

Multiple Ajax calls sometimes fail

I have a PHP script which queries a database and returns a table, depending on the input, e.g.results.php?f=1.
I am trying to call it multiple times from JavaScript:
function go(n,divid) {
document.getElementById(divid).innerHTML = "<img src=\"load.gif\">";
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function () {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
document.getElementById(divid).innerHTML = xmlhttp.responseText;
}
}
xmlhttp.open("GET", n, true);
xmlhttp.send();
}
Call later
go('results.php?print=1&nh=1','d1');
go('results.php?print=2&nh=1','d2');
go('results.php?print=3&nh=1','d3');
go('results.php?print=4&nh=1','d4');
The PHP code connects to a SQLite3 database. The problem with the above is that sometimes it works, but sometimes one of the queries fails to be prepared by SQLite3::prepare().
What could be wrong? A sqlite race condition? A javascript issue?
When results.php is called just once, the query always succeeds.
Thanks.

Use xhttp instead of xmlhttp.
function go(n,divid) {
var xhttp = new XMLHttpRequest();
document.getElementById(divid).innerHTML = "<img src=\"load.gif\">";
xhttp.onreadystatechange = function () {
if (xhttp.readyState == 4 && xhttp.status == 200) {
document.getElementById(divid).innerHTML = xhttp.responseText;
}
}
xhttp.open("GET", n, true);
xhttp.send();
}
go('results.php?print=1&nh=1','d1');

Timeout method after hitting the url

We have the following method to invoke the URL using ajax.
Currently after hitting the url we are using the response.
So we want to put a timeout for reposne.So when we invoke the url if the response didn't came after 2sec then call one more method and if resp comes within two seconds call other mehtod.
We have tried using the timeout,but unable to made it working with the code.
function ajaxCall(url1) {
var ajaxresp = null;
var xmlhttp;
if (window.XMLHttpRequest) {
xmlhttp = new XMLHttpRequest();
} else {
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.open("GET", url1, true);
xmlhttp.send();
xmlhttp.onreadystatechange = function () {
if (xmlhttp.readyState == 4) {
if (xmlhttp.status == 200) {
ajaxresp = xmlhttp.responseText;
//function call
getAdResponse(ajaxresp);
}
}
}
}
Please advice me how to proceed.

Try smth like this
xmlhttp.open("GET",url1,true);
xmlhttp.onreadystatechange= function (){
if (xmlhttp.readyState==4){
if (xmlhttp.status == 200){
ajaxresp = xmlhttp.responseText;
}
}
xmlhttp.send();
setTimeout(function() {
if(ajaxresp) {
dosmth(ajaxresp);
} else {
dosmthelse();
}
}, 2000);

How can I send more than one variable to a php file using ajax and a get request?

I am trying to send an I.D. value and a name value to a php file using ajax. I can send just the I.D. variable just fine but when I try to add the name variable, the function stops working. How can I send both?
This works:
function click() {
var name = clickedelement.getElementsByTagName('input')[0].value;
var id = clickedelement.getElementsByTagName('input')[1].value;
if (window.XMLHttpRequest) {
xmlhttp = new XMLHttpRequest();
} else {
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
document.getElementById("popupBox").innerHTML = xmlhttp.responseText;
}
}
xmlhttp.open("GET", "friends2.php?id="+id, true);
xmlhttp.send();
};
But when I try to add the name variable, it dosnt work.
function click() {
var name = clickedelement.getElementsByTagName('input')[0].value;
var id = clickedelement.getElementsByTagName('input')[1].value;
if (window.XMLHttpRequest) {
xmlhttp = new XMLHttpRequest();
} else {
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
document.getElementById("popupBox").innerHTML = xmlhttp.responseText;
}
}
xmlhttp.open("GET", "friends2.php?id="+id"&name="+name, true);
xmlhttp.send();
};

change to "friends2.php?id="+id+"&name="+name you just have a missing +

"friends2.php?id="+id+"&name="
// missing plus sign here ^

cannot reach readystate=4

I go this AJAX code that worked fine, but when I moved it to a new file it stopped working.
I managed to find out that the readystate isn't 4 and status isn't 200.
The code was given to my in class by the teacher. It worked find until I made new file.
<script type = "text/javascript">
var request = false;
if (window.XMLHttpRequest)
request = new XMLHttpRequest();
else if (window.AciveXObject)
request = new ActiveXObject("Microsoft.XMLHTTP");
function login(PhpFile,divId,frm)
{
if (request)
{
var obj = document.getElementById(divId);
request.open("POST",PhpFile);
//setting the header
request.setRequestHeader('Content-Type','application/x-www-form- urlencoded');
request.onreadystatechange = function()
{
if (request.readyState == 4 &&
request.status == 200){
obj.innerHTML =request.responseText;
}
else
{
alert("here");
}
}
request.send("log="+frm.log.value+"&pwd="+frm.pwd.value);
}
}
</script>

if you alert(request.responseText) in that else case, that may give you more information

'application/x-www-form- urlencoded'
should be
'application/x-www-form-urlencoded'