xmlhttp request status always returns 0

Question

I have a function which does get requests using plain old JS.

function get(url,funct){
    var xmlhttpget = (window.XMLHttpRequest) ? new XMLHttpRequest() : new ActiveXObject("Microsoft.XMLHTTP");
    xmlhttpget.onreadystatechange=function(){
        if (xmlhttpget.readyState==4 && xmlhttpget.status==200){
            funct(xmlhttpget.responseText);
        }
    }
    xmlhttpget.open("GET",url,true);
    xmlhttpget.send();
}

I use it like this:

get(url, function(resp){ window.alert(resp); });

When my callback function stopped working I modified my get() function to the following for debugging:

function get(url,funct){
    var xmlhttpget = (window.XMLHttpRequest) ? new XMLHttpRequest() : new ActiveXObject("Microsoft.XMLHTTP");
    xmlhttpget.onreadystatechange=function(){
        window.alert("ready state: "+xmlhttpget.readyState+" // status: "+xmlhttpget.status);
        if (xmlhttpget.readyState==4 && xmlhttpget.status==200){
            window.alert("responded...");
            funct(xmlhttpget.responseText);
        }
    }
    window.alert(url);
    xmlhttpget.open("GET",url,true);
    xmlhttpget.send();
}

With this I discovered that, during each readystate change the readystate will progress from 1 to 2 to 4, but the status always stays at 0 so my callback is never called, however, when I copy the alerted url to the browser it works fine.

What's going on? Is my browser caching the page? How can I fix it (set a specific header on the requested page with php??)?

Oh, not sure if this is relevant, but the page that's calling the function is inside of a frame whose parent document includes the same JavaScript file.

Use a library like jQuery for ajax requests. It saves you from a lot of headaches. — TiMESPLiNTER, Oct 03 '14 at 14:34
@TiMESPLiNTER: Libraries aren't needed. XHR is simple enough. — , Oct 03 '14 at 14:39
How are you calling the function? Button click, link, form submit, etc? — epascarello, Oct 03 '14 at 14:40
You can prevent browser caching by appending GET parameter with current timestamp to URL: `url + '?_=' + (new Date()).getTime()`. jQuery does so. — hindmost, Oct 03 '14 at 14:42
no, I'm developing on localhost but the page i'm requesting is live. — I wrestled a bear once., Oct 03 '14 at 14:42
ooh, can't do cross domain? do I need to use a local php page and curl the remote file? — I wrestled a bear once., Oct 03 '14 at 14:43
@Adelphia — There are lots of options. That is one of that. But having established this is a same origin policy issue, this is a dupe. (There should be a really helpful error message on your JS console about access control headers). — Quentin, Oct 03 '14 at 14:46
@hindmost: If it was cached, there'd still be a status code. @Adelphia: Does that mean the page is `localhost` but the `XHR` is not? If so, yes you'll likely have a cross domain issue. Search around for that issue, and you'll get lots of good info. — , Oct 03 '14 at 14:47
Yes, ok thanks for all your time. If anyone cares to put it as the answer I will accept :) — I wrestled a bear once., Oct 03 '14 at 14:48
I'll look around for a duplicate, but I'm curious, you're using an `alert()` for debugging. Are you aware of your browser's developer tools? Like @Quentin mentioned, you'll get helpful info there. — , Oct 03 '14 at 14:49
yeah, but alert() stops further execution whereas logging does not. For that reason I tend to gravitate towards `alert()` — I wrestled a bear once., Oct 03 '14 at 14:52
True. Funny thing is that most of the searches I did for a dupe came up with questions about jQuery AJAX requests... because Libraries are easier??? ;-P Anyway, someone else found a dupe, but if you need more info, there's lots of questions about cross-domain requests around. — , Oct 03 '14 at 14:58

score 0 · Accepted Answer · answered Oct 03 '14 at 14:44

0

Try printing the statusText of the object. You may run into the browsers security policy.

answered Oct 03 '14 at 14:44

Zenorbi

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Returns empty string `window.alert("ready state: "+xmlhttpget.readyState+" // status: "+xmlhttpget.status+" Status text: "+xmlhttpget.statusText);` – I wrestled a bear once. Oct 03 '14 at 14:46
What is the URL of the website initiating the request and what is the URL you're calling? – Zenorbi Oct 03 '14 at 14:53
We've established the issue is cross domain request. The correct answer was mentioned in the above comments. – I wrestled a bear once. Oct 03 '14 at 14:55
Why did I receive a down vote? The answer was cross domain issue, which is a browser security policy and some browsers report "No Transport" in the statusText. – Zenorbi Oct 03 '14 at 15:09
I didn't downvote but +1 for that last comment, I didn't know that. – I wrestled a bear once. Oct 03 '14 at 15:17

xmlhttp request status always returns 0

1 Answers1