Develop Reference

POST with Javascript AJAX

I am currently writing some poll software and, even though it works fine, I am having difficulties getting some of my javascript to work. I have a button labelled "Add New Option" which, when clicked, will call the following javascript function:
function newoption()
{
var option = "";
while((option.length < 1)||(option.length > 150))
{
var option = prompt("Please enter the option value... ").trim();
}
var add = confirm("You entered " + option + ", are you sure?");
if(add==1)
{
var code = window.location.href.length;
var poll = prompt("Which poll are you adding this to?", window.location.href.substring(code - 5, code));
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200)
{this.responsetext = option;}};
xhttp.open("POST", "../special/new.php", true);
xhttp.send("poll=" + poll + "&opt=" + option);
}
else
{
alert("OK... try again");
}
}
The page it posts to simply has a function to add the option to the poll which the user supplies the code for (it automatically gets this from the end of the URL) but the problem is that, when I refresh the page, the list of options is not updated which makes me think it isn't being added to the database but the function to add new options works on when the poll is created. Is there something I'm doing wrong?
The code for new.php is:
<?php require("internal/index.php");
$option = string_format($conection, $_POST["opt"], 1)
$poll =(int) $_POST["poll"];
if($poll&&$option)
{
new_poll_option($connection, $poll, $option);
}
?>

From what you wrote I understand that the code works until you refresh the page. That means that you don't check the Ajax response and just insert some HTML which will last until you refresh the page.
You need to look in your database if the items was created. If it is created then maybe you need to delete the browser cache (you can do that from the Network tab in DevTools in Chrome).
If the items was not insert in the database then you need to debug or just echo the message from the insert function that you used.
You can also use a form and not use Ajax if you will refresh the page anyway in a few moments.

how to ajax for chatting website without page reload

want to create a fully dynamic chat UI for my website, But it reloads the whole page if a person submits the button page should not reload like many chat website.
<form action="action.php" method="post" id="formpost">
<input type="text" id="input" value="php echo">
<input type="submit" value="send">
</form>
I want to submit this form through ajax and show the last xml <message> containing <message>talk 123<message>
<messages category="short">
<person1>
<time>
r
<message>Djssjs</message>
</time>
</person1>
<person2>
<time>
r
<message>1234fdg</message>
</time>
</person2>
<person1>
<time>
r
<message> talk 123</message>
</time>
</person1>
</messages>
i want to show that talk 123 in the html document bit confused how to do that
//for form submit
$("#formpost").submit(function(e) {
var form = $(this);
var url = form.attr('action');
$.ajax({
type: "POST",
url: action.php,
data: form.serialize(), // serializes the form's elements.
success: function(data)
{
alert(data); // show response from the php script.
}
});
e.preventDefault(); // avoid to execute the actual submit of the form.
});
//for xml
function loadDoc() {
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
myFunction(this);
}
};
xhttp.open("GET", "name.xml", true);
xhttp.send();
}
function myFunction(xml) {
var xmlDoc = xml.responseXML;
var msg = "";
//how to select the last person's of the <messages> child
msg = getElementsByTagName("messages").lastChild.childNodes[1].nodeValue ;
document.getElementById("demo").innerHTML = msg;
}

$("#formpost").on('submit', function(event){
event.preventDefault();
// rest of your ajax code here...
});
Points to note
1. Make sure you have also added JQuery script source on the head tag of your chat page.
2. Make sure to put preventDefault() immediately before any other code is executed.

You can use reverse ajax method pulling data from the server.
In reverse ajax a request is auto-generated at a certain time interval or hold the request for fetching new message.
There are three technologies for reverse ajax:-
Piggyback
Polling
Comet

Dynamic Form Action URL

I'm trying to create a form on my website where a user has a text field that they can use to enter a registration number. I want the registration number to be added to the end of the action URL so when that page loads I can use PHP to explode the URL and grab the number. Here's an example of what I'm looking for...
<form action="http://mywebsite.com/registrations/123456789">
<input type="text" name="registrationnumber">
<input type="Submit" value="Submit">
</form>
Is it possible to take whatever is entered into the text field called registrationnumber and have it passed to the URL the form directs to? Maybe an easier way is to create a text field that has a button, when the button is clicked the URL is links to is dynamically created by adding the registrationnumber to the end.
Anyone know of a way to do this?

Indeed you don't need a form to make an AJAX call. A simple input and button will suffice.
I have made a function that will make AJAX call, it will convert the object params containing all key/value pairs of the parameters you want to send to PHP, and concatenates it into a URL string:
function ajax(file, params, callback) {
var url = file + '?';
// loop through object and assemble the url
var notFirst = false;
for (var key in params) {
if (params.hasOwnProperty(key)) {
url += (notFirst ? '&' : '') + key + "=" + params[key];
}
notFirst = true;
}
// create a AJAX call with url as parameter
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
callback(xmlhttp.responseText);
}
};
xmlhttp.open('GET', url, true);
xmlhttp.send();
}
Assuming you have an input field:
<input id="code" type="text">
<button id="sendData">Send</button>
Here's how we can use the function ajax:
function sendData() {
parameters = {
inputValue: document.querySelector('#code').value
};
ajax('target.php', parameters, function(response) {
// add here the code to be executed when data comes back to client side
// e.g. console.log(response) will show the AJAX response in the console
});
}
You can then attach the button to sendData using an event listener:
document.querySelector('#sendData').addEventListener('click', sendData)

Avoid identical client ajax request on refresh

I would like to test if the ajax request is identical so it can be aborted or some other alert action taken?
In reality clients can change the request via a few form elements then hit the refresh button.
I have made a poor attempt at catching the identical request. Need to keep the timer refresh functionality.
<script type="text/javascript" src="http://code.jquery.com/jquery-latest.js"></script>
<script type="text/javascript">
var current_request_id = 0;
var currentRequest = null;
var lastSuccessfulRequest = null;
function refreshTable() {
$('#select').html('Loading');
window.clearTimeout(timer);
//MY CATCH FOR DUPLICATE REQUEST NEEDS WORK
if (lastSuccessfulRequest == currentRequest)
{
//currentRequest.abort();
alert('Duplicate query submitted. Please update query before resubmission.');
}
var data = {
"hide_blanks": $("#hide_blanks").prop('checked'),
"hide_disabled": $("#hide_disabled").prop('checked'),
};
json_data = JSON.stringify(data);
current_request_id++;
currentRequest = $.ajax({
url: "/calendar_table",
method: "POST",
data: {'data': json_data},
request_id: current_request_id,
beforeSend : function(){
if(currentRequest != null) {
currentRequest.abort();
}
},
success: function(response) {
if (this.request_id == current_request_id) {
$("#job_table").html(response);
$("#error_panel").hide();
setFixedTableHeader();
}
},
error: function(xhr) {
if (this.request_id == current_request_id) {
$("#error_panel").show().html("Error " + xhr.status + ": " + xhr.statusText + "<br/>" + xhr.responseText.replace(/(?:\r\n|\r|\n)/g, "<br/>"));
}
},
complete: function(response) {
if (this.request_id == current_request_id) {
$("#select").html("Refresh");
window.clearTimeout(timer);
stopRefreshTable();
window.refreshTableTimer = window.setTimeout(refreshTable, 10000);
lastSuccessfulRequest = currentRequest;
}
}
});
}
//TIMER STUFF TO refreshTable()
//THIS SECTION WORKS FINE
var startDate = new Date();
var endDate = new Date();
var timer = new Date();
function startRefreshTable() {
if(!window.refreshTableTimer) {
window.refreshTableTimer = window.setTimeout(refreshTable, 0);
}
}
function stopRefreshTable() {
if(window.refreshTableTimer) {
self.clearTimeout(window.refreshTableTimer);
}
window.refreshTableTimer = null;
}
function resetActive(){
clearTimeout(activityTimeout);
activityTimeout = setTimeout(inActive, 300000);
startRefreshTable();
}
function inActive(){
stopRefreshTable();
}
var activityTimeout = setTimeout(inActive, 300000);
$(document).bind('mousemove click keypress', function(){resetActive()});
</script>
<input type="checkbox" name="hide_disabled" id="hide_disabled" onchange="refreshTable()">Hide disabled task<br>
<br><br>
<button id="select" type="button" onclick="refreshTable();">Refresh</button>

I'd use the power of .ajaxSend and .ajaxSuccess global handlers.
We'll use ajaxSuccess to store a cache and ajaxSend will try to read it first, if it succeeds it will trigger the success handler of the request immediately, and abort the request that is about to be done. Else it will let it be...
var ajax_cache = {};
function cache_key(settings){
//Produce a unique key from settings object;
return settings.url+'///'+JSON.encode(settings.data);
}
$(document).ajaxSuccess(function(event,xhr,settings,data){
ajax_cache[cache_key(settings)] = {data:data};
// Store other useful properties like current timestamp to be able to prune old cache maybe?
});
$(document.ajaxSend(function(event,xhr,settings){
if(ajax_cache[cache_key(settings)]){
//Add checks for cache age maybe?
//Add check for nocache setting to be able to override it?
xhr.abort();
settings.success(ajax_cache[cache_key(settings)].data);
}
});
What I've demonstrated here is a very naïve but functional approach to your problem. This has the benefit to make this work for every ajax calls you may have, without having to change them. You'd need to build up on this to consider failures, and to make sure that the abortion of the request from a cache hit is not getting dispatched to abort handlers.

One valid option here is to JSON.Stringify() the objects and compare the strings. If the objects are identical the resulting serialised strings should be identical.
There may be edge cases causing slight differences if you use an already JSONified string directly from the response so you'll have to double check by testing.
Additionally, if you're trying to figure out how to persist it across page loads use localStorage.setItem("lastSuccessfulRequest", lastSuccessfulRequest) and localStorage.getItem("lastSuccessfulRequest"). (If not, let me know and I'll remove this.)

Submit Embedded Mailchimp Form with Javascript AJAX (not jQuery)

I have been trying to submit an embedded Mailchimp form with AJAX but without using jQuery. Clearly, I am not doing this properly, as I keep ending up on the "Come, Watson, come! The game is afoot." page :(
Any help with this would be greatly appreciate.
The form action has been altered to replace post?u= with post-json?u= and &c=? has been added to the end of the action string. Here is my js:
document.addEventListener('DOMContentLoaded', function() {
function formMailchimp() {
var elForm = document.getElementById('mc-embedded-subscribe-form'),
elInputName = document.getElementById('mce-NAME'),
elInputEmail = document.getElementById('mce-EMAIL'),
strFormAction = elForm.getAttribute('action');
elForm.addEventListener('submit', function(e) {
var request = new XMLHttpRequest();
request.open('GET', strFormAction, true);
request.setRequestHeader('Content-Type', 'application/json; charset=UTF-8');
request.onload = function() {
if (request.status >= 200 && request.status < 400) {
// Success!
var resp = JSON.parse(request.responseText);
request.send(resp);
} else {
console.log('We reached our target server, but it returned an error');
}
};
request.onerror = function() {
console.log('There was a connection error of some sort');
};
});
}
formMailchimp();
});
Also, I anticipate the inevitable "why don't you just use jQuery" comment. Without going into the specifics of this project, jQuery is not something I am able to introduce into the code. Sorry, but this HAS to be vanilla javascript. Compatibility is for very modern browsers only.
Thanks so much for any help you can provide!

A few days back I've had the exact same problem and as it turns out the MailChimp documentation on native JavaScript is pretty sparse. I can share with you my code I came up with. Hope you can build from here!
The simplified HTML form: I've got the from action from the MailChimp form builder and added "post-json"
<div id="newsletter">
<form action="NAME.us1.list-manage.com/subscribe/post-json?u=XXXXXX&id=XXXXXXX">
<input class="email" type="email" value="Enter your email" required />
<input class="submit" type="submit" value="Subscribe" />
</form>
</div>
The JavaScript: The only way to avoid the cross-origin problem is to create a script and append it to the header. The callback occurs then on the “c” parameter. (Please note there is no email address validation on it yet)
function newsletterSubmitted(event) {
event.preventDefault();
this._form = this.querySelector("form");
this._action = this._form.getAttribute("action");
this._input = this._form.querySelector("input.email").value;
document.MC_callback = function(response) {
if(response.result == "success") {
// show success meassage
} else {
// show error message
}
}
// generate script
this._script = document.createElement("script");
this._script.type = "text/javascript";
this._script.src = this._action + "&c=document.MC_callback&EMAIL=" + this._input;
// append script to head
document.getElementsByTagName("head")[0].appendChild(this._script);
}
var newsletter = document.querySelector("#newsletter")
newsletter.addEventListener("submit", newsletterSubmitted);