Develop Reference

AJAX is returning readystate=1

I am using Flask with Python. From the Flask method I am trying to return HTML table rows in an AJAX call.
The HTML page has:
<div>
<table id="tableQuestions">
</table>
//AJAX Requests to get
function loadQuestions() {
var xmlHttp = new XMLHttpRequest();
xmlHttp.onreadystatechange = function() {
alert(xmlHttp.readyState + " " + xmlHttp.status);
if (xmlHttp.readyState==4 && xmlHttp.status == 200) {
var response = xmlHttp.responseText;
console.log(response);
document.querySelector("#tableQuestions").innerHTML=response;
}
xmlHttp.open("GET", '/gS', true);
xmlHttp.send(null);
}
}
The Flask route has:
#test.mix() returns html table rows
#gbp.route('/gS')
def gS():
test=mn()
response = make_response(test.mix(quesCount=4),200)
response.mimetype="text/html"
In the Safari debugger I can see that the responseText has the table data from the server, but readystate remains 1 and status = 0.
Could you please suggest how I can overcome this issue?

You have
xmlHttp.open("GET", '/gS', true);
xmlHttp.send(null);
inside your xmlHttp.onreadystatechange callback function, which leads to strange effects.
The following code (untested) should behave better:
//AJAX Requests to get
function loadQuestions() {
var xmlHttp = new XMLHttpRequest();
xmlHttp.open("GET", '/gS', true);
xmlHttp.onreadystatechange = function() {
alert(xmlHttp.readyState + " " + xmlHttp.status);
if (xmlHttp.readyState==4 && xmlHttp.status == 200) {
var response = xmlHttp.responseText;
console.log(response);
document.querySelector("#tableQuestions").innerHTML=response;
}
}
xmlHttp.send(null);
}

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');

AJAX xmlhttp.open sumit data using POST method

I am trying to send a form data using POST method and xmlhttp.open
Please help find the error in my code
function submitChat() {
if (form1.msg.value == '' ) {
alert ('ALL FIELDS ARE MANDATORY');
return;
}
var xmlhttp = new XMLHttpRequest();
var msg = form1.msg.value;
var params = 'msg=helloooooooo';
xmlhttp.onreadystatechange = function () {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
document.getElementById('chatlogs').innerHTML = xmlhttp.responseText;
}
}
xmlhttp.open('POST', 'rtest.php?rid=14', true);
xmlhttp.send(params);
}
Everything is fine and it is working with GET method. but POST method is not working. Please help.

Ajax call not successful

I am making a javascript function call on onclick of any checkbox like this:
function getPGCountList(pageNo) {
var url = "someJsp.jsp?" + pageNo;
alert(1);
if (window.XMLHttpRequest) {
alert(2);
xmlhttp = new XMLHttpRequest();
} else {
alert(3);
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
alert(4);
xmlhttp.onreadystatechange = function () {
alert(5);
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
alert(6);
document.getElementById("searchForPage").innerHTML = xmlhttp.responseText;
}
};
alert(7);
xmlhttp.open("GET", url, true);
alert(8);
xmlhttp.send();
}
The alert output I am getting is at my hosted site:
1-2-4-7-5-8-5-5-5
But in my local system it is:
1-2-4-7-5-8-5-5-5-6
I need to execute alert 6 also to change the content.
I am not sure where is the problem?

Your code looks fine to me. Check the path to someJsp.jsp
It's obviously not returning a normal response from the ajax call otherwise it would enter your if block and fire alert 6.
Just a thought too, but if you alert xmlhttp.readyState and xmlhttp.status maybe it'll help you find your problem. IF they are undefined, or refer to an object that is undefined, then your new XMLHttp requests failed. IF they give you results, you can see what the responses mean

send an http request without XHR in an event handler

How to send an http request with either post/get method using javascript as an eventhandler? Thanks! Paul

Okay, you don't want to use Ajax.
You can use an event handler to submit a form!
<a href='#' onclick='cow_submit("zoodle")'>send</a>
<form method='post' id='formie' action='find_some_action.php'>
<input type='hidden' id='snoutvar' name='snoutvar' value='snout'>
</form>
<script>
function cow_submit(a_var_to_set){
var plip=document.getElementById('formie');
var snout=document.getElementById('snoutvar');
snout.value=a_var_to_set;
plip.submit();
}
See https://developer.mozilla.org/en/DOM/form

use XmlHttpRequest
sample code:
var client = new XMLHttpRequest();
client.onreadystatechange = handler;
client.open("GET", "test.xml");
client.send();
function handler()
{
// your handler
}

You can use XMLHttpRequest for sending request from javascript
Sending GET request
var url = "get_data.php";
var params = "lorem=ipsum&name=binny";
http.open("GET", url+"?"+params, true);
http.onreadystatechange = function() {//Call a function when the state changes.
if(http.readyState == 4 && http.status == 200) {
alert(http.responseText);
}
}
http.send(null);
Sending POST request
var url = "get_data.php";
var params = "lorem=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.setRequestHeader("Content-length", params.length);
http.setRequestHeader("Connection", "close");
http.onreadystatechange = function() {//Call a function when the state changes.
if(http.readyState == 4 && http.status == 200) {
alert(http.responseText);
}
}
http.send(params);
And don't forget to encode parameters using encodeURIComponent for param value encoding in case of user input
e.g.
params="paramName="+encodeURIComponent(paramValue);

The standard class for doing this is XmlHttpRequest, but it's not universally supported. On some browsers you have to use ActiveXObject("Microsoft.XMLHTTP") instead.
Look into the jQuery system which provides HTTP download (AJAX style) methods regardless of the underlying browser APIs (hence avoiding a lot of the code shown in Tzury's answer).
The jQuery AJAX documentation is at http://docs.jquery.com/Ajax

You should try to add atring in a hidden field and then call the form.submit() to submit your form into the page define in action.
<script type="text/javascript">
function doTestFormSubmit(yourString) {
document.getElementById("myString").value=myString;
document.getElementById("testForm").submit();
}
</script>
<form name="testForm" id="testForm" action="yourDesiredPage.php" method="post">
<input type="hidden" name="myString" id="myString" value=""/>
</form>

Ajax Tutorial (http://code.google.com/edu/ajax/tutorials/ajax-tutorial.html)
var obj;
function ProcessXML(url) {
// native object
if (window.XMLHttpRequest) {
// obtain new object
obj = new XMLHttpRequest();
// set the callback function
obj.onreadystatechange = processChange;
// we will do a GET with the url; "true" for asynch
obj.open("GET", url, true);
// null for GET with native object
obj.send(null);
// IE/Windows ActiveX object
} else if (window.ActiveXObject) {
obj = new ActiveXObject("Microsoft.XMLHTTP");
if (obj) {
obj.onreadystatechange = processChange;
obj.open("GET", url, true);
// don't send null for ActiveX
obj.send();
}
} else {
alert("Your browser does not support AJAX");
}
}
function processChange() {
// 4 means the response has been returned and ready to be processed
if (obj.readyState == 4) {
// 200 means "OK"
if (obj.status == 200) {
// process whatever has been sent back here:
// anything else means a problem
} else {
alert("There was a problem in the returned data:\n");
}
}
}