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How to send a string to php with POST [duplicate]

This question already has answers here:
Send POST data using XMLHttpRequest
(13 answers)
Closed 8 years ago.
I'm sending a string via xmlhttp in javascript using the following code:
function SendPHP(str, callback) {
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 && xmlhttp.status == 200) {
callback(xmlhttp.responseText); //invoke the callback
}
}
xmlhttp.open("GET", "testpost.php?q=" + encodeURIComponent(str), true);
xmlhttp.send();
}
and some test php:
$q = $_GET['q'];
echo $q;
That worked fine until I started sending a larger string in which case I get the "HTTP/1.1 414 Request-URI Too Long" error.
After a bit of research I found out I need to use "POST" instead. So I changed it to:
xmlhttp.open("POST", "sendmail.php?q=" + str, true);
And:
$q = $_POST['q'];
echo $q;
But this does not echo anything when using POST. How can I fix it so it works like when I was using GET but so it can handle a large string of data?
edit I'm now trying it with:
function testNewPHP(str){
xmlhttp = new XMLHttpRequest();
str = "q=" + encodeURIComponent(str);
alert (str);
xmlhttp.open("POST","testpost.php", true);
xmlhttp.onreadystatechange=function(){
if (xmlhttp.readyState == 4){
if(xmlhttp.status == 200){
alert (xmlhttp.responseText);
}
}
};
xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xmlhttp.send(str);
}

You should not provide your href with URL parameters, instead of this you should send() them. For addition, you should always encode your parameters with encodeURIComponent() (At least when your request is using the Content-type "application/x-www-form-urlencoded").
your javascript function :
function testNewPHP(){
var str = "This is test";
xmlhttp = new XMLHttpRequest();
str = "q=" + encodeURIComponent(str);
alert (str);
xmlhttp.open("POST","testpost.php", true);
xmlhttp.onreadystatechange=function(){
if (xmlhttp.readyState == 4){
if(xmlhttp.status == 200){
alert (xmlhttp.responseText);
}
}
};
xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xmlhttp.send(str);
}

javascript :
function testNewPHP(){
var str = "This is test";
xmlhttp = new XMLHttpRequest();
str = "q=" + encodeURIComponent(str);
alert (str);
xmlhttp.open("POST","testpost.php", true);
xmlhttp.onreadystatechange=function(){
if (xmlhttp.readyState == 4){
if(xmlhttp.status == 200){
alert (xmlhttp.responseText);
}
}
};
xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xmlhttp.send(str);
}
testpost.php in your home directory :
<?php
var_dump($_POST);
OUTPUT :
array(1) {
["q"]=>
string(12) "This is test"
}

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);

Javascript does not return servlet response

I have wriiten welcome screen which basically use below javascript to call creditCheck servlet. Within servlet, there is method which will check the username and password. Servlet returns value properly. alert is not getting generated after servlet excutation within javascript.
however if execute simple servlet ( not doing anything, just printing variables), it will generate alert.
below is my javascript within JSp file:
############################################
<script type="text/javascript">
function getXmlHttpRequestObject(){
var xmlHttp = false;
if (window.XMLHttpRequest){
return new XMLHttpRequest(); //To support the browsers IE7+, Firefox, Chrome, Opera, Safari
}
else if(window.ActiveXObject){
return new ActiveXObject("Microsoft.XMLHTTP"); // For the browsers IE6, IE5
}
else {
alert("Error due to old verion of browser upgrade your browser");
}
}
var xmlhttp = new getXmlHttpRequestObject(); //xmlhttp holds the ajax object
function servletPost() {
if(xmlhttp) {
var username = document.getElementById("uname");
var password = document.getElementById("pass");
xmlhttp.open("POST","CredCheck",true);
xmlhttp.onreadystatechange = handleServletPost;
req.onreadystatechange = callback;
xmlhttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
xmlhttp.send("uname=" + username.value + "&pass=" + password.value );
}
}
function handleServletPost() {
if (xmlhttp.readyState == 4) {
if(xmlhttp.status == 200) {
alert(xmlhttp.responseText);
}
else {
alert("Ajax calling error");
}
}
}
</script>
#

I have changed xmlhttp.open("POST","CredCheck",true); to
xmlhttp.open("POST","CredCheck",false);
xmlhttp.onreadystatechange = handleServletPost;

Javascript and AJAX trough outside function

function ajax_request(destination_full_url) {
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 && xmlhttp.status == 200) {
alert("response: \n" + xmlhttp.responseText);
return xmlhttp.responseText;
}
}
xmlhttp.open("GET", destination_full_url, true);
xmlhttp.send();
}
function third_party_function(obj) {
var response
response = ajax_request("info.php?keyword=obj.value");
alert(response);
}
<textarea onkeypress="third_party_function(this);"></textarea>
First comes off message box "underfined" one second after comes off message box with ajax request.
Question is why it runs alert(response); before finishing the previous step and how i make it wait untill ajax_request() function finished before going to next line?

because ajax is asynchronous and runs in background by default, you can make it synchronous by changing from
xmlhttp.open("GET", destination_full_url, true);
to
xmlhttp.open("GET", destination_full_url, false);
=== update ===
function ajax_request(destination_full_url, callback){
.....
xmlhttp.onreadystatechange = function () {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
alert("response: \n" + xmlhttp.responseText);
callback(xmlhttp.responseText);
}
}
...
}
....
function third_party_function(obj) {
ajax_request("info.php?keyword=obj.value", function(response){alert(response) });
}

Simple XMLHttpRequest (Google Weather)

Hello I want to get xml from Google Weather
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.open("GET", "http://www.google.com/ig/api?weather=london&hl=en", true);
xmlhttp.send(null);
xmlDoc=xmlhttp.responseXML;
It`s not working . Thanks

XMLHttpRequest is asynchronous. You need to use a callback. If you don't want to use a full-fledged library, I recommend using Quirksmode's XHR wrapper:
function callback(xhr)
{
xmlDoc = xhr.responseXML;
// further XML processing here
}
sendRequest('http://www.google.com/ig/api?weather=london&hl=en', callback);
If you absolutely insist on implementing this yourself:
// callback is the same as above
var xmlhttp;
if (window.XMLHttpRequest)
{
xmlhttp = new XMLHttpRequest();
}
else
{
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.open("GET", "http://www.google.com/ig/api?weather=london&hl=en", true);
xmlhttp.onreadystatechange = function ()
{
if (xmlhttp.readyState != 4) return;
if (xmlhttp.status != 200 && xmlhttp.status != 304) return;
callback(xmlhttp);
};
xmlhttp.send(null);
Edit
As #remi commented:
I think you'll get a cross domain access exception : you can't make an ajax request to an other domain than your page's. no ?
Which is (for the most part) correct. You'll need to use a server-side proxy, or whatever API that Google provides, instead of a regular XHR.

You can't do this via javascript to to it being a cross-domain request. You'd have to do this server-side.
In PHP you'd use CURL.
What you are trying to do can't be done with Javascript.

Ok here is the code :
<html>
<body>
<script type="text/javascript">
var xmlhttp;
var xmlDoc;
function callback(xhr)
{
xmlDoc = xhr.responseXML;
// further XML processing here
}
if (window.XMLHttpRequest)
{
xmlhttp = new XMLHttpRequest();
}
else
{
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.open("GET", "http://www.google.com/ig/api?weather=london&hl=en", true);
xmlhttp.onreadystatechange = function ()
{
if (xmlhttp.readyState != 4) return;
if (xmlhttp.status != 200 && xmlhttp.status != 304) return;
callback(xmlhttp);
};
xmlhttp.send(null);
alert(xmlDoc);
</script>
</body>
</html>
It doesn`t returns any errors but alert returns undefined.