I'm fairly new to the world of web development and am trying to read a txt file in internet explorer 8 and compare it to source code of a website to see if they are equal. This is so I can work out if the web page is functioning correctly.
I managed to get the source code with an xmlhttprequest and have tried the same to get the text file (which is in the same domain as my web page) and I am getting an access denied error.
After some research I can see that cross-domain xmlhttprequests won't work but that's not what I'm trying to do so I'm not sure how to proceed.
Having run the same code in Firefox(current version). It will read the file but not the web page!
I don't mind which of the two browsers I end up using but at the moment each does half of what I want it to.
my code is:
function source1(){
xmlhttp=new XMLHttpRequest();
xmlhttp.open("GET", "http://website",true);
xmlhttp.onreadystatechange=function() {
if (xmlhttp.readyState==4) {
document.getElementById('textzone').value = xmlhttp.responseText
var inputString = xmlhttp.responseText;
alert(inputString);
comparison(inputString)
}
}
xmlhttp.send(null)
}
function comparison(inputString){
xmlhttp1=new XMLHttpRequest();
xmlhttp1.open("GET", "comparisondoc.txt", false);
xmlhttp1.onreadystatechange=function() {
if (xmlhttp1.readyState==4) {
var compareString = xmlhttp1.responseText;
alert(compareString)
if(inputString==compareString){
alert("Strings are equal");
}
}
}
xmlhttp.send(null)
}
All I need to know is why either the file won't open in ie8, or why the website source code shows up blank (in the alert) in firefox. Any help would be appreciated.
It could be a browser support issue.
Try the following code to initialize your XMLHttpRequest :
function createRequest() {
try {
request = new XMLHttpRequest();
} catch (trymicrosoft) {
try {
request = new ActiveXObject("Msxml2.XMLHTTP");
} catch (othermicrosoft) {
try {
request = new ActiveXObject("Microsoft.XMLHTTP");
} catch (failed) {
request = false;
}
}
}
if (!request)
alert("Error initializing XMLHttpRequest!");
}
Check your comparison function. You should you xmlhttp1 instead of xmlhttp at 2 places
function comparison(inputString){
xmlhttp1=new XMLHttpRequest();
xmlhttp1.open("GET", "comparisondoc.txt", false);
xmlhttp1.onreadystatechange=function() {
if (xmlhttp1.readyState==4) {
<!--alert(xmlhttp1.responseText)-->
var compareString = xmlhttp1.responseText;
alert(compareString)
if(inputString==compareString){
alert("Strings are equal");
}
}
}
xmlhttp1.send(null)
}
Try to add the if(xmlhttp.status == 200) { } stuff. Remember both of these are looping through status' "AND" readystates.
Technically you could be erroring somewhere (I'd rather not speculate on) halting progress to next request or whatever without the status check.
Also you "should" try other request techniques. ie.. xmlhttp.onreadystatechange = function(){itsReady(inputString)}; // we keep this line short and simple calling to another func that contains your status and readystate checks, response stuff, and more func.
On a pretty normal run the Loop looks like:
hi rdySte:1///status 0////////
hi rdySte:2///status 200////////
hi rdySte:3///status 200////////
hi rdySte:4///status 200////////
I ran into a lot of weird issues trying the long onreadystatechange = function (){ ... All stuff..} I successfully run a crazy set of request functionalities using the short onreadystatechange technique.
I noticed at the last minute->
is there a reason why the async flags are different between your funcs? I'd set them all to true unless you have a great reason.
This will work: (to test: 2 pages t1.php contains a num or whatever and t2.txt that has a num in sam dir as the funcs are called in)
function source1(){
var avar = 1;
xmlhttp=new XMLHttpRequest();
xmlhttp.open("GET", "t1.php",true); // shortened f-names for ease of test
xmlhttp.onreadystatechange = function(){jsg_snd(avar)};
xmlhttp.send(null)
}
function jsg_snd(avar){
if (xmlhttp.readyState==4) {
if (xmlhttp.status == 200) {
var inputString = xmlhttp.responseText;
document.getElementById('text_zone').innerHTML = inputString;
document.getElementById('text_zone1').value = inputString;
// alert(inputString);//
comparison(inputString)
}
}
}
function comparison(inputString){
xmlhttp1=new XMLHttpRequest();
xmlhttp1.open("GET", "t2.txt", true);
xmlhttp1.onreadystatechange= function(){jsg_snd1(inputString);};
xmlhttp1.send(null)
}
function jsg_snd1(inputString){
if (xmlhttp1.readyState==4) {
if (xmlhttp1.status == 200) {
var compareString = xmlhttp1.responseText;
//alert(compareString)
if(inputString==compareString){
//alert("Strings are equal");
document.getElementById('text_zone').innerHTML += "; Ok "+inputString+"=="+compareString+"";
}
}
}
}
Now the html in your body should look like:
<tt id = 'text_go' onMouseUp="source1();" >Go!</tt>
<tt id = 'text_zone' onMouseUp="text_zone.innerHTML = '';" >Click to clear!</tt>
<input type ='text' id = 'text_zone1' onMouseUp="text_zone1.value = '';" value = 'Click to clear!' >
The extra stuf is for ___s & giggles.
Related
I am using AJAX to display upcoming events on a website. To that end, I call a JavaScript function via onload="showEvents(3);", see the function below:
function showEvents (amount) {
// are there Events?
if (document.getElementById("eventsDiv")) {
document.getElementsByClassName("info")[0].innerHTML = 'Loading events...';
// initialize XML Http Request
var xmlhttp;
if (window.XMLHttpRequest) {
xmlhttp = new XMLHttpRequest();
} else {
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange = function () {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
document.getElementById("eventsDiv").innerHTML = xmlhttp.responseText;
}
}
// send request
xmlhttp.open("GET", "./events.php?number=" + encodeURIComponent(amount), true);
xmlhttp.setRequestHeader("Content-Type", "text/plain;charset=UTF-8");
xmlhttp.send();
}
}
The file events.php is a PHP file in the same directory, and it connects to the database to fetch the upcoming events. The HTML header of the main website includes
<base href="http://www.my-domain.com/">
The problem: I get a "Cross Orign" error message (in Firefox), preventing my parent index.html file accessing the events.php. As I understand, this error message should not appear since I am using a resource from the same directory.
Ok that's ok, you also can do like this...
if($_SERVER['HTTP_ORIGIN'] == "http://your-domain.com") {
header('Access-Control-Allow-Origin: http://your-domain.com');
How can I detect whether an Ajax request failed to load a file.
Here is my code for reference:
var pro = undefined;
var xmlhttp;
if (window.XMLHttpRequest){
xmlhttp = new XMLHttpRequest();
}
else{
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange = function(){
if (xmlhttp.readyState==4 && xmlhttp.status==200){
pro = JSON.parse(xmlhttp.responseText);
}
}
xmlhttp.open("GET","data.json",true);
xmlhttp.send();
Please, no jQuery.
Thanks!
you can check if the http status is 500 or more than 500 which means an error occurred in the request http://en.wikipedia.org/wiki/List_of_HTTP_status_codes#5xx_Server_Error
if (xmlhttp.status >= 500){
alert('error');
}
NOTE: you can also consider other http status numbers as you like
onerror callback should be used for handling error, like this:
xmlhttp.onerror = function onError(e) {
alert("Error " + e.target.status + " occurred while receiving the document.");
}
As far as I know, jQuery library also uses this method. Not sure which all browsers support this, but this surely works in firefox.
What I do is use a global variable I name 'boomerang' (witty I know)
so when you send the request out make boomerang=1 and then on its success make boomerang=0
then at some appropriate time after you send the request out then you can just check if boomerang =1 or =0
you need to check the status code- 4xx and 5xx codes are errors.
here's a list of codes: http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
You won't need much more. Do something in the else clause other than the comment.
xmlhttp.onreadystatechange = function(){
if (xmlhttp.readyState==4 && xmlhttp.status==200){
pro = JSON.parse(xmlhttp.responseText);
} else {
if (xmlhttp.readyState==4) {
// Something failed
}
}
}
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
I am trying to write a streamlined version of a XMLHttpRequest demo script shown here:
http://www.w3schools.com/ajax/tryit.asp?filename=tryajax_first
I'm only going to use this on iPad, so I don't have to check for older versions of IE, and so on. On button click, I want to check if the connection exists. Here's my entire html page, including JavaScript snippet:
<html>
<head>
<script>
var myURL = "http://www.google.com";
function testConnection(url) {
var xmlhttp;
xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function () {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
alert("Connected!");
} else {
alert("Not connected!");
}
}
xmlhttp.open("GET", url, true);
xmlhttp.send();
}
</script>
</head>
<body>
<button type="button" onclick="testConnection(myURL)">Test Connection</button>
</body>
</html>
For some weird reason, even though I'm online, when I click the button, I get repeated "Not connected" alerts, and only after a while I get the "Connected" alert, followed by no alerts.
Looks like I messed up, but I can't see where. What should I change to make it work?
If you can use xhr2, you can learn stuff from this tutorial and rewrite your code to something like this:
function testConnection(url) {
var xmlhttp = new XMLHttpRequest();
xmlhttp.onload = function() { alert("Connected!"); }
xmlhttp.onerror = function() { alert("Not Connected"); }
xmlhttp.open("GET",url,true);
xmlhttp.send();
}
If you send request to another domain, you may get error even if it exists, if the target server has Same-Domain-Policy restriction (default). If the target server is on another domain, it must send header
Access-Control-Allow-Origin: *
I'm trying to make an ajax call to an external domain that is already allowing external requests by sending Access-Control-Allow-Origin:* header, but i get Permission Denied on the xmlhttp.post() line.
Here is my code:
var xmlhttp;
try {
xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
try {
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
} catch (E) {
xmlhttp = false;
}
}
if (!xmlhttp && typeof XMLHttpRequest != 'undefined') {
try {
xmlhttp = new XMLHttpRequest();
} catch (e) {
xmlhttp = false;
}
}
xmlhttp.onreadystatechange = function () {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
alert(xmlhttp.responseText);
}
}
xmlhttp.open("GET", "http://www.domain.com", true);
xmlhttp.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
xmlhttp.send();
I believe that in IE, you still can't use XMLHttpRequest for cross domain requests. For that, you need to use XDomainRequest object. Full documentation is here. I believe the reason for introducing the separate object was to allow developers to do a compatibility test before making a request that certainly would fail with older browsers.
I believe you can only use Ajax with URL's form the same domain as your calling page. It's not the external domain that disallows the request, it's your browser's security. Take a look at Same Origin Policy
This is a way to avoid cross browser scripts - otherwise imagine you have a page where you can enter your credit card info and someone injects a script that sends information you are typing to an external site. Would be a big problem to fight.
Note :Do not use "http://domain.xxx" or "http://localhost/" or "IP" for URL in Ajax.
Only use path(directory) and page name without address.
false state:
var AJAXobj = createAjax();
AJAXobj.onreadystatechange = handlesAJAXcheck;
AJAXobj.open('POST', 'http://www.example.com/dir1/dir2/page.php', true);
AJAXobj.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded; charset=UTF-8');
AJAXobj.send(pack);
true state:
var AJAXobj = createAjax();
AJAXobj.onreadystatechange = handlesAJAXcheck;
AJAXobj.open('POST','dir1/dir2/page.php', true); // <<--- note
AJAXobj.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded; charset=UTF-8');
AJAXobj.send(pack);
function createAjax()
{
var ajaxHttp = null;
try
{
if(typeof ActiveXObject == 'function')
ajaxHttp = new ActiveXObject("Microsoft.XMLHTTP");
else
if(window.XMLHttpRequest)
ajaxHttp = new XMLHttpRequest();
}
catch(e)
{
alert(e.message);
return null;
}
//-------------
return ajaxHttp;
};