There is a javascript line (you can try it in the browser console)
window.location.href='http://example.com'
that will push you to http://example.com
In the Browser(Google Chrome)-> Developer Tools-> Network section you may see the Status is 200 for it.
The question is:
how to get the status code 200/404/302 right BEFORE executing
window.location.href='http://example.com'
Thank you.
P.S. jQuery is OK for using.
The only way to get the status code would be to make the request before you navigate there. That means make an Ajax call to the resource and check the status. Only downside to this is the Same Origin Policy so the sites need to be in the same domain or they have to have CORS enabled for your resource.
The HTTP status code are generated by the server, so some HTTP request against the server needs to be executed BEFORE you can get a status code -- so you would need to do an Ajax call on the url -- adapting the simple example in JQuery.get you will have something like;
$.get( "http://example.com", function( data ) {
// Yeahh the URL works, we can do the page switch
window.location.href='http://example.com';
});
There are other examples in JQuery.get which deals with error handling etc, but you can read those for yourself.
Of cause, you don't need the entire page to get just the status, you can execute just a HTTP-HEAD which you can see discussed here
With all of this you may run into cross-site scripting restrictions which you can go an research separately -- there are lot of stack-overflow questions on that already.
I have the following.
AJAX request made to server from mydomain.blah.com
Server returns 302 but to a slight different domain blah.com not mydomain.blah.com
Browser appears to mangle response. Instead of the 302 coming into my error callback a response with no response body and no status code is returned.
Further details
Looking at request in IE 10 it is marked as aborted.
In FF , firebug shows the 302 coming back but it never been handled.
To complicate matters (although I don't this is relevant) there are multiple ajax requests sent over.
The reason why the 302 is returned is because my server session is timed out and I am being redirected to a login page. I don't have much control over the server.
I want to get the response code 302 sent from my server into my error callback. This is what I want to achieve.
The ajax calls are being made using JQuery.
Any help appreciated.
If it is offical policy for browsers to "mangle" 302 responses to difference domains from ajax calls then if anyone could provide a reference that would be cool. Then I'd know there is not much I can do about this.
I've a server that returns HTTP status code 200, 201, and 202 from the same url. In Chrome, I've confirmed with the Network debugging panel that the Status Code is what I expect it to be (i.e. 200, 201 or 202). I rely on that status code to determine the next step.
I'd expect that the callbacks for jQuery (version 1.5.2) AJAX requests to set jqxhr.status to the status code that the server sends. However, the status code is always 200, even if the code sent by the server is 201 or 202.
In other words, the following code prints Code: 200 regardless of what the server sends.
$.get(url, {}, function (data, textStatus, xhr ) {
alert("Code: " + xhr.status);
});
Why is this happening, and more importantly, how can one get the actual status code in a jQuery AJAX callback for $.get or $.ajax?
Thank you for reading.
From what I have experienced jQuery is just not set up very well for handling actual status codes in the response. You can try just doing a manual AJAX call using some good old bare bones JS and handle the status yourself.
Here are a few tutorials on how to do so.
http://www.degraeve.com/reference/simple-ajax-example.php
http://www.w3schools.com/ajax/default.asp
request.status is where you should be able to access the status code in your request object. Here is another page showing a little bit about how to access even more granular information about the status of the request.
http://www.ibm.com/developerworks/web/library/wa-ajaxintro3/
Hope that helps you nail it!
I use the jQuery ajax functions to access a web service, but the server, instead of returning a response with a status code describing a problem, the request is redirected to a page with a 200 header, describing the problem. I can't make any changes to this, so I need to solve it on the client somehow.
Example:
A request goes to some URL which is not found, so I receive a 302 Redirect to another location. A new request is sent, and I receive a 200 OK, thus preventing the error callback to fire.
Is there some way I can prevent the ajax request to follow redirects and instead invoke a callback, preferably the error method. Alternatively, is it possible to detect if a redirect has happened in the client?
I find your question interesting, but the problem in whole seems me more a misunderstanding. At least I'll try to explain my understanding of the problem.
The silent (transparent) redirection is the part of XMLHttpRequest specification (see here especially the words "... transparently follow the redirect ..."). The standard mention only that the user agent (the web browser) can prevent or notify of certain kinds of automatic redirections, but it's not a part of XMLHttpRequest. It's the part of HTTP client configuration (OS configuration) or the web browser configuration. So jQuery.ajax can't have any option where you can prevent redirection.
You can see that HTTP redirection is the part of HTTP protocol and not a part of XMLHttpRequest. So it's on the another level of abstraction or the network stack. For example the data from the XMLHttpRequest can be retrieved from the HTTP proxy or from the local browser cache, and it's the part of HTTP protocol. Mostly the server which provide the data and not the client can influence on caching.
You can compare the requirement from your question with the requirement to prevent changing of IP address of the web server or the changing of the IP route during the communication. All the things can be interesting in some scenarios, but there are parts of another level of the communication stack and can't be managed by jQuery.ajax or XMLHttpRequest.
The XMLHttpRequest standard say that the client configuration can have options which prevent redirection. In case of "Microsoft world", which I better know, you can look at WinHttpSetOption function which can be used to set WINHTTP_OPTION_DISABLE_FEATURE option with the WINHTTP_DISABLE_REDIRECTS value. Another way are the usage of WINHTTP_OPTION_REDIRECT_POLICY option with the WINHTTP_OPTION_REDIRECT_POLICY_NEVER value. One more feature which one can use in Windows is the WinHttpSetStatusCallback function which can set callback function received some notifications like WINHTTP_CALLBACK_FLAG_REDIRECT.
So it's do possible to implement your requirements in general, but the solution will be probably not independent from the operation system or the web browser and be not on the level of jQuery.ajax or XMLHttpRequest.
I don't believe it is possible. The underlying library (XHR) makes the new request transparently. That being said, what I have done in these situations (usually a session-timeout type of deal that takes me to a login page) is send back a custom response header. I also have setup a global ajax handler that checks for the presence of that header, and responds appropriately when present (for example, redirecting the whole page to the login screen).
In case you're interested, here's the jQuery code I have to watch for that custom header:
/* redirects main window when AJAX request indicates that the session has expired on the backend. */
function checkSession(event, xhr, ajaxOptions)
{
if (xhr.readyState == 4)
{
if(xhr.getResponseHeader("Login-Screen") != null && xhr.getResponseHeader("Login-Screen").length)
{
window.location.href='sessionExpired.html'; //whatever
}
}
}
$(document).ajaxComplete(checkSession)
I found a feature to check if your call has been redirected. It's xhr.state(): if it's "rejected" then a redirection happened.
Example with success callback:
request.success(function(data, textStatus, xhr)
{
if(xhr.state() == "resolved")
{
//no redirection
}
if(xhr.state() == "rejected")
{
//redirection
}
});
Example with error callback:
request.error(function(xhr, textStatus)
{
if (xhr.state() == "rejected")
{
//redirection
location.href = "loginpage";
} else
{
//some other error happened
alert("error");
}
});
I can't possibly add to the insightful wisdom of the previous coders who've responded, but I will add a specific case that others may find useful to know about.
I came across this 302 silent redirect in the context of SharePoint. I have some simple Javascript client code that pings a SharePoint sub-site, and if it receives a 200 HTTP response, it relocates to that site, via window.location. If it receives anything else, it gives the user a notice that the site doesn't exist.
However, in the case where the site exists but the user does not have permission, SharePoint silently redirects to an AccessDenied.aspx page. SharePoint has already done the HTTP 401 authentication handshake at the server/farm level - the user has access to SharePoint. But the access to the sub-site is handled I suppose using database flags of some sort. The silent redirect bypasses my "else" clause, so I can't throw up my own error. In my case, this is not a show-stopper - it is consistent predictable behavior. But it was a little surprising, and I learned something about HTTP requests in the process!
I was interested in the same thing and could not find the state() method mentioned by Takman and did a little digging for myself. For the sake of people turning up here in search of an answer, here are my findings:
As stated multiple times, you cannot prevent redirects, but you can detect them. According to MDN you can use the responseURL of the XMLHttpRequestObject, which will contain the final URL the response came from, after all redirects. Only caveat is that it is not supported by Internet Explorer (Edge has it). Since the xhr/jqXHR passed into the success/done function of jquery is an extension of the actual XMLHttpRequest, it should be available there, too.
While it is not possible to disable location redirect following in XmlHttpRequests, it is when using fetch():
fetch('url', {redirect: manual});
I suppose you receive a 200 response because the second time there is no redirection, because the 404 page does not expire, it is saved in the cache. That is to say that the second time the browser gives you the page in the cache.
There is a property "cache" in the ajax jquery.
http://api.jquery.com/jQuery.ajax/
You should write it to "false"
I'm not sure if this will apply in your case, but you can write code to respond to specific status codes in AJAX function -
$.ajax({
url: '/admin/secret/data',
type: 'POST',
contentType: 'application/json; charset=utf-8',
statusCode: {
200: function (data) {
alert('302: Occurred');
// Bind the JSON data to the UI
},
401: function (data) {
alert('401: Occurred');
// Handle the 401 error here.
}
}
});
In the request headers in the case of ajax request you will have the following
X-Requested-With XMLHttpRequest
By this criteria on the server side you can filter requests.
I am implementing an application which relies upon communication between a JavaScript client and a server which knows how to respond to the client using JSONP notation.
I am attempting to handle the case in my Javascript client where my server returns with an http status code of 4xx or 5xx. Currently what I'm seeing is that the script is not evaluated as the browser believes it to be an error (which it is.) However, I still want to read what my server has to say in the event of this 4xx or 5xx response code in my JavaScript client.
I'm seeing that this does raise an error on the script tag element, but I'm concerned that this is not cross browser and will not be a robust solution.
Has anyone had any luck on still parsing a jsonp response even though the http status code is 4xx or 5xx?
I'm beginning to believe I should just use this "set a timeout" solution which "detects" a failure by stating the callback function to the jsonp request would complete within a certain time frame, and if it doesn't, there was an error.
EDIT: I'm temporarily always returning 200 status code when my server detects a jsonp client and then tunneling the error message/status in the json object returned. I was hoping to take advantage of the HTTP status codes but I'm thinking that is no-go for a javscript client.
JSONP is a hack to work-around cross-domain issues. When it works, it works well. But when it doesn't you don't have a way to figure out what went wrong.
setTimeout is another hack on top of the original one. If you must use JSONP and still need error detection (not handling), thats what you'd have to do. There isn't a better solution.
If you control the server, try to use alternatives such as Cross-Origin-Resource-Sharing (CORS), or Flash's crossdomain.xml to allow cross domain requests. If you don't control the server, you can proxy the response through your server to get better control.
One approach when using JSONP is to embed status information in the callback. So the callback function signature would look like
callback(result, status, message)
So if your call looks like
http://myurl.com/?callback=fn
generate code for a successful call that looks like
fn({"data":"my great data"}, 200)
and for an exceptional condition
fn(null, 500, "server error"}
You can check the status of the XHR object (if you are not using a JS library).
if(xhr.readyState == 4){
if(xhr.status == 200){
// good
}else if(xhr.status == 502){
// d'oh
}
}
If you are using jQuery, you can pass in a statusCode to handle special cases for $.ajax