Post html form triggering ajax request NO JQuery - javascript

I have an old js code working fine for ajax requests WITHOUT JQuery:
function makeGetRequestTar(key) {
http.open('GET', key, true);
//assign a handler for the response
http.onreadystatechange = processResponseTar;
//actually send the request to the server
http.send(null);
}
function processResponseTar() {
if(http.readyState == 4){
var response = http.responseText;
document.getElementById('content').innerHTML = response;
}
}
But now i want to:
Trigger the ajax request when submitting an html form
Pass the 'content' in document.getElementById('content').innerHTML as a variable.
Continue WITHOUT JQuery
So this is my js code now:
function makeGetRequestTar(fileTarget, htmlTarget) {
http.open('GET', fileTarget, true);
//assign a handler for the response
http.onreadystatechange = processResponseTar(htmlTarget);
//actually send the request to the server
http.send(null);
}
function processResponseTar(htmlTarget) {
if(http.readyState == 4){
var response = http.responseText;
document.getElementById(htmlTarget).innerHTML = response;
}
}
And here the html:
<div id="description-form">
<form enctype="multipart/form-data" id="xxx" action="receiver.php" method="post" target="my-iframe">
<textarea class="proposal" name="description" rows="10" cols="60"></textarea>
<br>
<input class="submitbutton" type="submit" onclick="return makeGetRequestTar('doc/description.txt','description-preview')" value=" Save text " />
<br>
<iframe name="my-iframe" style="display:none"></iframe>
</form>
</div>
<div id="description-preview" style="float:left">
<?php include("doc/description.txt")?>
</div>
This code does not throw any error on the console. And the form is posted correctly via php.
But the ajax request is not working, why does it not work if there are no errors showing?

Your old code
http.onreadystatechange = processResponseTar;
assigns the callback function processResponseTar to the onreadystatechange event property.
The new code
http.onreadystatechange = processResponse(htmlTarget);
calls your callback (note the (..)). You can't add custom parameters to that callback. One way to make htmlTarget accessible to your callback is this:
function makeGetRequestTar(fileTarget, htmlTarget) {
http.open('GET', fileTarget, true);
//assign a handler for the response
http.onreadystatechange = function() {
processResponseTar(htmlTarget);
};
//actually send the request to the server
http.send(null);
}

The problem is that you are executing the function processReponse here:
http.onreadystatechange = processResponse(htmlTarget);
and assigning the RESULT of that function (which in this case is undefined) to http.onreadystatechange.
Now, when the readystate changes, XMLHttpRequest attempts to call onreadystatechange which is now undefined, so nothing happens.
Try this:
function processResponseTar(htmlTarget) {
return function () {
if(http.readyState == 4){
var response = http.responseText;
document.getElementById(htmlTarget).innerHTML = response;
}
}
}
Now, you are still assigning the result of the function to http.onreadystatechange, but this time it is a callable function instead of undefined.

First of all your http is undefined, you need to define that. And second, you're calling processResponse function but function name is processResponseTar.
Edited:
<script>
var http;
function makeGetRequestTar(fileTarget, htmlTarget) {
if(window.XMLHttpRequest){
http=new XMLHttpRequest(); // code for IE7+, Firefox, Chrome, Opera, Safari
}else{
http=new ActiveXObject("Microsoft.XMLHTTP"); // code for IE6, IE5
}
http.open('GET', fileTarget, true);
//assign a handler for the response
http.onreadystatechange = processResponseTar(htmlTarget);
//actually send the request to the server
http.send(null);
}
function processResponseTar(htmlTarget) {
return function () {
if(http.readyState == 4 && http.status==200){
var response = http.responseText;
document.getElementById(htmlTarget).innerHTML = response;
}
}
}
</script>

Related

POST value from JavaScript to PHP via AJAX without jQuery

I'm trying to send a JavaScript variable to be processed server-side by PHP then echo back the result. My ajax request results in readyState == 4 and status == 200 yet PHP keeps echoing back an empty array/value.
I'm pretty sure this comes from my Ajax call sending an empty request but everything I tried didn't work, so maybe I'm going all wrong here.
JS (from index.html) :
var valueToSend = Math.random();
var request = false;
if (window.XMLHttpRequest) {
request = new XMLHttpRequest();
}
else if (window.ActiveXObject) {
request = new ActiveXObject('Microsoft.XMLHTTP');
}
function send_ajax() {
if (request) {
request.open('POST', 'test.php', true);
request.onreadystatechange = function() {
if (request.readyState == 4 && request.status == 200) {
console.log(request.responseText);
}
}
request.send(valueToSend); //this line is probably not sending the value the way I expect it to
}
}
PHP (from test.php) :
echo $_POST['name']; //simple echo to check if PHP indeed receives valueToSend
My last try was to change request.send(valueToSend); with .send(encodeURI('name=' + valueToSend)); but it just made the ajax call redirect the page location to a non-existing one.
What am I doing wrong ?
There are few things wrong in your code, such as:
Even through you defined send_ajax() function, you didn't call it anywhere in the code.
With POST request you need to send an HTTP header setRequestHeader() along with the request, like this:
request.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
echo $_POST['name']; in test.php page won't work because name is undefined here. Your send() method call should be like this:
request.send("name="+valueToSend);
So the complete JavaScript code would be like this:
var valueToSend = Math.random();
var request = false;
if (window.XMLHttpRequest) {
request = new XMLHttpRequest();
}
else if (window.ActiveXObject) {
request = new ActiveXObject('Microsoft.XMLHTTP');
}
function send_ajax() {
if (request) {
request.open('POST', 'test.php', true);
request.onreadystatechange = function() {
if (request.readyState == 4 && request.status == 200) {
console.log(request.responseText);
}
}
request.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
request.send("name="+valueToSend);
}
}
send_ajax();

How to submit form without reloading page, without jQuery?

I have form as follows, it require to sent an action to my java Servlet to do an update to the database.
How do I submit the form without the page get reloaded here?
Currently with action="myServlet" it keep direct me to a new page. And if I remove the action to myServlet, the input is not added to my database.
<form name="detailsForm" method="post" action="myServlet"
onsubmit="return submitFormAjax()">
name: <input type="text" name="name" id="name"/> <br/>
<input type="submit" name="add" value="Add" />
</form>
In the view of my Java servlet, request.getParameter will look for the name and proceed to add it into my db.
#Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
if (request.getParameter("add") != null) {
try {
Table.insert(name);
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
In my JavaScript part, I have a submitFormAjax function
function submitFormAjax()
{
var xmlhttp;
if (window.XMLHttpRequest) {
// code for modern browsers
xmlhttp = new XMLHttpRequest();
} else {
// code for IE6, IE5
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200)
alert(xmlhttp.responseText); // Here is the response
}
var id = document.getElementById("name").innerHTML;
xmlhttp.open("POST","/myServlet",true);
xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xmlhttp.send("name=" + name);
}
A similar question was asked here
Submit form without reloading page
Basically, do "return false" after invoking the function. Something like this should work:
<form name="detailsForm"
method="post"
action="myServlet"
onsubmit="submitFormAjax();
return false;"
>
This is how I used to implement Ajax in JS without JQuery. As am a PHP and JS guy I cant possibly help you with Java Servlet side but yes heres my little help from JS side. This given example is a working example.See if it helps you.
// HTML side
<form name="detailsForm" method="post" onsubmit="OnSubmit(e)">
// THE JS
function _(x){
return document.getElementById(x);
}
function ajaxObj( meth, url )
{
var x = false;
if(window.XMLHttpRequest)
x = new XMLHttpRequest();
else if (window.ActiveXObject)
x = new ActiveXObject("Microsoft.XMLHTTP");
x.open( meth, url, true );
x.setRequestHeader("Content-type", "application/json");
return x;
}
function ajaxReturn(x){
if(x.readyState == 4 && x.status == 200){
return true;
}
}
function OnSubmit(e) // call this function on submit
{
e.preventDefault();
var username = _("name").value;
if (username == "")
{
alert("Fill out the form first");
}
else
{
var all = {"username":username};
all = JSON.stringify(all);
var url = "Myservlet";
var ajax = ajaxObj("POST", url);
ajax.onreadystatechange = function()
{
if(ajaxReturn(ajax) == true)
{
// The output text sent from your Java side in response
alert( ajax.responseText );
}
}
//ajax.send("user="+username+");
ajax.send(all);
}
}
Thanks
Change the code in form
onsubmit="submitFormAjax(event)"
Change your JS code
function submitFormAjax(e)
{
e.preventDefault();
var xmlhttp;
if (window.XMLHttpRequest) {
// code for modern browsers
xmlhttp = new XMLHttpRequest();
}
......
................
...............
return false; //at last line

Using AJAX to execute a PHP script through a JavaScript function

I have an anchor link with no destination, but it does have an onClick event:
<li><a href onClick='deletePost()'> Delete </a> </li>
I understand that I cannot directly execure PHP code blocks in JavaScript due to the nature of PHP and it being a server side language, so I have to utilize AJAX to do so.
When the delete link is clicked, I need it to execute this query (del_post.php)
<?php include("connect.php");
$delete_query = mysqli_query ($connect, "DELETE FROM user_thoughts WHERE id = 'id' ");
?>
I have tried to understand AJAX using similar past questions, but due to being relatively new, I cannot completely grasp it's language. Here is what I have tried:
function deletePost() {
xmlhttp=new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200){
xmlhttp.open("GET", "del_post.php", false);
xmlhttp.send();
}
}
}
But clicking the link just changes the URL to http://localhost/.
I believe the (main) problem is your empty "href" attribute. Remove that, or change it to href="#" or old school href="javascript:void()" (just remove it, imo).
It's been a while since I used XMLHttpRequest and not something like jQuery's .ajax, but I think you need to do it like so (mostly you need to .open/send before you watch for the state change):
var xmlHttpReq = new XMLHttpRequest();
if (xmlHttpReq) {
xmlHttpReq.open('GET', 'your-uri-here.php', true/false);
xmlHttpReq.onreadystatechange = function () {
if (xmlHttpReq.readyState == 4 && xmlHttpReq.status == 200) {
console.log('success! delete the post out of the DOM or some other response');
}
else {
console.log('there was a problem');
}
}
xmlHttpReq.send();
}
Can you please provide your : del_post.php file?
Normally you can show a text or alert in a
<div id="yourname"></div>
by using callback in an AJAX request :
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
document.getElementById("yourname").innerHTML = xmlhttp.responseText;
}
This response is coming from your PHP file for example :
function remove_record(ARG){
if ($condition==true)
echo "TRUE";
else
echo "FALSE";
}
You should remove href attribute from anchor tag and style the element with CSS.
Also, your script should look like this:
<script>
function deletePost() {
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (xhttp.readyState == 4 && xhttp.status == 200) {
// Do something if Ajax request was successful
}
};
xhttp.open("GET", "del_post.php", true);
xhttp.send();
}
</script>
You are trying to make the http request inside the callback.
You just need to move it outside:
function deletePost() {
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
alert(xmlhttp.responseText);
}
}
xmlhttp.open("GET", "del_post.php", false);
xmlhttp.send();
}
Removing the href attribute will prevent the refresh. I believe that is valid in HTML5.
Ok... I'm just a hobbyist, so please forgive me any inaccuracies in the typing but this works: A format I use for an ajax call in an <a> element is:
<a href="javascript:" onclick="functionThatReallyCallsAjax()">
So that I have more flexibility(in case I need to check something before I send the ajax). Now, for an ajax call you need:
What file to call
What to do with the response from the file you called
What to do if an I/O error happens
So we have this function - not mine, leeched amongst thousands from somewhere - probably here :) - and probably well known, my apologies to the author, he is a genius: This is what you call for the ajax thing, where 'url' is the file you want to 'ajax', 'success' is the name of the function that deals with results and error is the name of the function that deals with IO errors.
function doAjaxThing(url, success, error) {
var req = false;
try{
// most browsers
req = new XMLHttpRequest();
} catch (e){
// IE
try{
req = new ActiveXObject("Msxml2.XMLHTTP");
} catch(e) {
// try an older version
try{
req = new ActiveXObject("Microsoft.XMLHTTP");
} catch(e) {
return false;
}
}
}
if (!req) return false;
if (typeof success != 'function') success = function () {};
if (typeof error!= 'function') error = function () {};
req.onreadystatechange = function(){
if(req.readyState == 4) {
return req.status === 200 ?
success(req.responseText) : error(req.status);
}
}
req.open("GET", url, true);
req.send(null);
return req;
}
You will naturally need to include the success+error functions:
function dealWithResponse(textFromURL)
{
//textFromURL is whatever, say, a PHP you called in the URL would 'echo'
}
function ohNo()
{
//stuff like URL not found, etc.
alert("I/O error");
}
And now that you're armed with that, this is how you compose the real call inside the function you called at the <a>:
function functionThatReallyCallsAjax()
{
//there are probably many scenarios but by having this extra function,
//you can perform any processing you might need before the call
doAjaxThing("serverFile.php",dealWithResponse,ohNo);
}
One scenario might be when you need to pass a variable to the PHP you didn't have before. In this case, the call would become:
doAjaxThing("serverFile.php?parameter1=dogsRock",dealWithResponse,ohNo);
And now not only you have PHP sending stuff to JS, you have JS sending to PHP too. Weeeee...
Final words: ajax is not a language, its a javascript 'trick'. You don't need to fully understand what the first 'doAjaxThing' function does to use this, just make sure you are calling it properly. It will automatically 'call' the 'deal WithResponse' function once the response from the server arrives. Notice that you can continue doing your business (asynchronous - process not time-tied) till the response arrives - which is when the 'deal WithResponse' gets triggered -, as opposed to having a page stop and wait (synchronous - time tied) until a response arrives. That is the magic of ajax (Asynchronous JAvascript and Xml).
In your case you want to add the echo("success") - or error! - in the PHP, so that the function 'dealWithResponse' knows what to do based on that info.
That's all I know about ajax. Hope this helps :)

XMLHttpRequest.responseText doesnt write the value when calling a URL

There may be a small error in my code. please advice me.
I want to call a URL and display the value in div on pageload.I wrote this code from SO but the responseText doesnt write the value in the div element's innerhtml
Code
<script type="text/javascript" >
var req ;
// Browser compatibility check
if (window.XMLHttpRequest) {
req = new XMLHttpRequest();
} else if (window.ActiveXObject) {
try {
req = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
try {
req = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e) {}
}
}
var req = new XMLHttpRequest();
req.open("GET", "www.example.com/Default.aspx?usrname=john",true);
req.onreadystatechange = function () {
document.getElementById('divTxt').innerHTML = "My Status: " + req.responseText;
}
req.send(null);
</script>
<html>
<head/>
<body>
<div id="divTxt"></div></body>
</html>
The output I get is
My status :
PS: I want this to be done after pageload and The url returns a value "online" when called manually
EDIT
This is the code I referred : code
You cannot ajax a url from another domain unless it has implemented CORS
If you need to get data from somewhere which is not same origin you need to use JSONP
Also to debug, try calling the url from the locationbar to see if you receive valid data for your request
req.onreadystatechange = function () {
document.getElementById('divTxt').innerHTML = "My Status: " + req.responseText;
}
you have to check, if the request was successful:
if (req.readyState === 4) {
// what should be done with the result
}
finally, it has to look like this:
req.onreadystatechange = function () {
if (req.readyState === 4) {
document.getElementById('divTxt').innerHTML = "My Status: " + req.responseText;
}
}

jsp with ajax two simultaneous requests only getting one response

I have a jsp page where I'm trying to send multiple (two currently) ajax requests at once, but I only seem to get the second response. This guy described my problem exactly, but his solution didn't work for me.
Here is my js code:
function createRequestObject(){
var req;
if(window.XMLHttpRequest){
//For Firefox, Safari, Opera
req = new XMLHttpRequest();
} else if(window.ActiveXObject){
req = new ActiveXObject("Microsoft.XMLHTTP");
}
else{
//Error for an old browser
alert('Browser error');
}
return req;
}
function sendRequest(method, url, d){
var http = createRequestObject();
var div = d;
if(method == 'get' || method == 'GET'){
http.open(method, url, true);
http.onreadystatechange = function() {
if(http.readyState == 4 && http.status == 200){
var response = http.responseText;
if(response){
document.getElementById(div).innerHTML = response;
}
}
};
http.send(null);
}
}
And here is how I call that code:
QC1 Status: <div id='qc1'>blah</div>
<br />UAT2 Status: <div id='uat2'>blah2</div>
<a onclick="sendRequest('GET','index.jsp?qc1.properties=true','qc1'); " href="#">qc1</a>
<a onclick="sendRequest('GET','index.jsp?uat2.properties=true','uat2'); " href="#">uat2</a>
<a onclick="sendRequest('GET','index.jsp?qc1.properties=true','qc1'); sendRequest('GET','index.jsp?uat2.properties=true','uat2'); " href="#">both</a>
When I call one at a time they work as expected, but the "both" link only updates with the second request, even though I know it runs the index.jsp code for both.
EDIT: Ok, after fixing the obvious mistake that BalusC pointed out, it works. Fixed it in this post too.
You're indeed sending two requests on the same URL and updating the same div. Shouldn't the first one go to the qc1 one and update the qc1 one?

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