Mozilla’s XMLHttpRequest is modelled after Microsoft’s IXMLHttpRequest
object. The goal has been to make Mozilla’s version match Microsoft’s
version as closely as possible, but there are bound to be some differences.
In general, Microsoft’s documentation for IXMLHttpRequest can be used.
Mozilla’s interface definitions provide some additional documentation. The
web page to look at is http://www.mozilla.org/xmlextras/
Mozilla’s XMLHttpRequest object can be created in JavaScript like this:
new XMLHttpRequest()
compare to Internet Explorer:
new ActiveXObject(“Msxml2.XMLHTTP”)
From JavaScript, the methods and properties visible in the XMLHttpRequest
object are a combination of nsIXMLHttpRequest and nsIJSXMLHttpRequest;
there is no need to differentiate between those interfaces.
From native code, the way to set up onload and onerror handlers is a bit
different. Here is a comment from Johnny Stenback jst@netscape.com:
The mozilla implementation of nsIXMLHttpRequest implements the interface
nsIDOMEventTarget and that’s how you’re supported to add event listeners.
Try something like this:
nsCOMPtr
target->AddEventListener(NS_LITERAL_STRING(“load”), mylistener,
PR_FALSE)
where mylistener is your event listener object that implements the
interface nsIDOMEventListener.
The ‘onload’, ‘onerror’, and ‘onreadystatechange’ attributes moved to
nsIJSXMLHttpRequest, but if you’re coding in C++ you should avoid using
those.
Conclusion: Do not use event listeners on XMLHttpRequest from C++, unless
you’re aware of all the security implications. And then think twice about
it.
If the request has been sent already, this method will
abort the request.
Returns all of the response headers as a string for HTTP
requests.
| A string containing all of the response headers. The empty string if the response has not yet been received. |
Returns the text of the header with the specified name for
HTTP requests.
| header | The name of the header to retrieve |
| A string containing the text of the header specified. NULL if the response has not yet been received or the header does not exist in the response. |
Meant to be a script-only method for initializing a request.
If there is an “active” request (that is, if open() has been called
already), this is equivalent to calling abort() and then open().
| method | The HTTP method - either "POST" or "GET". Ignored if the URL is not a HTTP URL. |
| url | The URL to which to send the request. |
| async | (optional) Whether the request is synchronous or asynchronous i.e. whether send returns only after the response is received or if it returns immediately after sending the request. In the latter case, notification of completion is sent through the event listeners. The default value is true. |
| user | (optional) A username for authentication if necessary. The default value is the empty string |
| password | (optional) A password for authentication if necessary. The default value is the empty string |
Sends the request. If the request is asynchronous, returns
immediately after sending the request. If it is synchronous
returns only after the response has been received.
All event listeners must be set before calling send().
After the initial response, all event listeners will be cleared.
// XXXbz what does that mean, exactly?
| body | Either an instance of nsIDOMDocument, nsIInputStream or a string (nsISupportsString in the native calling case). This is used to populate the body of the HTTP request if the HTTP request method is "POST". If the parameter is a nsIDOMDocument, it is serialized. If the parameter is a nsIInputStream, then it must be compatible with nsIUploadChannel.setUploadStream, and a Content-Length header will be added to the HTTP request with a value given by nsIInputStream.available. Any headers included at the top of the stream will be treated as part of the message body. The MIME type of the stream should be specified by setting the Content- Type header via the setRequestHeader method before calling send. |
A variant of the send() method used to send binary data.
| body | The request body as a DOM string. The string data will be converted to a single-byte string by truncation (i.e., the high-order byte of each character will be discarded). |
Sets a HTTP request header for HTTP requests. You must call open
before setting the request headers.
| header | The name of the header to set in the request. |
| value | The body of the header. |
Override the mime type returned by the server (if any). This may
be used, for example, to force a stream to be treated and parsed
as text/xml, even if the server does not report it as such. This
must be done before the send method is invoked.
| mimetype | The type used to override that returned by the server (if any). |
Initialize the object for use from C++ code with the principal, script
context, and owner window that should be used.
| principal | The principal to use for the request. This must not be null. |
| scriptContext | The script context to use for the request. May be null. |
| globalObject | The associated global for the request. Can be the outer window, a sandbox, or a backstage pass. May be null, but then the request cannot create a document. |
| baseURI | The base URI to use when resolving relative URIs. May be null. |
The request uses a channel in order to perform the
request. This attribute represents the channel used
for the request. NULL if the channel has not yet been
created.
Mozilla only. Requires elevated privileges to access.
The response to the request is parsed as if it were a
text/xml stream. This attributes represents the response as
a DOM Document object. NULL if the request is unsuccessful or
has not yet been sent.
The response to the request as text.
NULL if the request is unsuccessful or
has not yet been sent.
Determine a response format which response attribute returns.
empty string (initial value) or “text”: as text.
“arraybuffer”: as a typed array ArrayBuffer.
“blob”: as a File API Blob.
“document”: as a DOM Document object.
The response to the request as a specified format by responseType.
NULL if the request is unsuccessful or
has not yet been sent.
The status of the response to the request for HTTP requests.
The string representing the status of the response for
HTTP requests.
The amount of milliseconds a request can take before being terminated.
Initially zero. Zero means there is no timeout.
Set to true if this is a background service request. This will
prevent a load group being associated with the request, and
suppress any security dialogs from being shown * to the user.
In the cases where one of those dialogs would be shown, the request
will simply fail instead.
When set to true attempts to make cross-site Access-Control requests
with credentials such as cookies and authorization headers.
Never affects same-site requests.
Defaults to false.
| Upload process can be tracked by adding event listener to | upload | . |
Meant to be a script-only mechanism for setting a callback function.
The attribute is expected to be JavaScript function object. When the
readyState changes, the callback function will be called.
This attribute should not be used from native code!!
After the initial response, all event listeners will be cleared.
// XXXbz what does that mean, exactly?
Call open() before setting an onreadystatechange listener.
If true, the request will be sent without cookie and authentication
headers.
If true, the same origin policy will not be enforced on the request.
The state of the request.
Possible values:
0 UNSENT open() has not been called yet.
1 OPENED send() has not been called yet.
2 HEADERS_RECEIVED
send() has been called, headers and status are available.
3 LOADING Downloading, responseText holds the partial data.
4 DONE Finished with all operations.