XMLHttpRequest to get HTTP response from remote host
Question
Why the following code Based on Mozilla example does not work? Tried with Firefox 3.5.7 & Chrome.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
</head>
<body>
</body>
<script>
var req = new XMLHttpRequest();
req.open('GET', 'http://www.mozilla.org/', false);
req.send();
if(req.status == 200) {
alert(req.responseText);
}
</script>
</html>
Please that the browser is pulling the html from local disk (file:///C:/Users/Maxim%20Veksler/Desktop/XMLHTTP.html)
On Firefox it gives the following error:
uncaught exception: [Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIXMLHttpRequest.send]" nsresult: "0x80004005 (NS_ERROR_FAILURE)" location: "JS frame :: file:///C:/Users/Maxim%20Veksler/Desktop/XMLHTTP.html :: <TOP_LEVEL> :: line 10" data: no]
What am I doing wrong? I want to submit a request to remote host and alert the result (later to added into a div).
4 answers
solution1
11 ACCPTED 2010-01-13 22:04:16
Your browser is preventing cross-site scripting . You have to use a relative path, otherwise most browsers will simply return an error or an empty responseText.
The following Stack Overflow post is probably also related to your problem:
solution2
3 2010-01-13 22:11:13
I'm also assuming that you've opened your HTML test page directly in the browser judging by your reference to file:///... . For XMLHttpRequest calls, you need to serve the HTML from a server. Try something like xampp ( http://www.apachefriends.org/en/xampp.html ) to get a local server up and running and then run your test from http://localhost/XMLHTTP.html .
Note, this does not solve your same-origin problem, but this would allow the following code to work:
<script>
var req = new XMLHttpRequest();
req.open('GET', '/myTestResponse.html', false);
req.send();
if(req.status == 200) {
alert(req.responseText);
}
</script>
solution3
0 2010-01-13 21:56:34
Security issue no?
Presumably firefox is preventing the local file from talking to a remote host?
Scouting round the net - found this. Try adding this to the start of your script:
try {
netscape.security.PrivilegeManager.enablePrivilege("UniversalBrowserRead");
} catch (e) {
alert("Permission UniversalBrowserRead denied.");
}
Can't guarantee this'll work; because ultimately what you're trying to do is enter a security hole that browsers have been specifically coded to have plugged up (cross-domain requests).
There are some special scenarios where it can be switched on, though, usually at the user's discretion.
solution4
0 2010-01-13 22:00:54
You cannot make requests across domains, even with local files.
https://developer.mozilla.org/en/Same_origin_policy_for_JavaScript
Unless you are developing an extension, which does not have the same restrictions as a web page.
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