Assigns method, destination URL, and other optional attributes of a pending request.
Syntax
XMLHttpRequest.open(sMethod, sUrl [, bAsync] [, sUser] [, sPassword])
Parameters
| sMethod |
Required.
String that specifies the HTTP method used to open the connection: such as GET, POST, or HEAD. This parameter is not case-sensitive. |
| sUrl |
Required.
String that specifies either the absolute or a relative URL of the XML data or server-side XML Web services. |
| bAsync |
Optional.
Variant that specifies
true for asynchronous operation (the call returns immediately), or
false for synchronous operation.
If true, assign a callback handler to
the onreadystatechange property
to determine when the call has completed.
If not specified, the default is true.
Performance Note
When bAsync
is set to
false, send operations are synchronous, and
Windows Internet Explorer does not accept input or produce output while
send operations are in progress.
Therefore, this setting should not be used
in situations where it is possible
for a user to be waiting on the
send operation
to complete.
|
| sUser |
Optional.
Variant that specifies the name of the user for authentication. If this parameter is null ("") or missing and the site requires authentication, the component displays a logon window. |
| sPassword |
Optional.
Variant that specifies the password for authentication. This parameter is ignored if the user parameter is null ("") or missing. |
Return Value
No return value.
Remarks
open was introduced in Internet Explorer 7.
The following
HTTP verbs and
World Wide Web Distributed Authoring and Versioning (WebDAV) methods 
are supported:
Internet Explorer caches the results of HTTP GET requests in the Temporary Internet Files (TIF) folder. In most cases, caching improves performance for data that will not change frequently. To guarantee that the results are not cached, use POST.
Security Alert Cross-domain, cross-port, and mixed protocol requests are not allowed. The
sUrl
parameter may only specify files in the same domain, using the same port and protocol method, as that from which the page is served.
Although this method accepts credentials passed via parameter, those credentials are not automatically sent to the server on the first request. The sUser
and sPassword
parameters are not transmitted unless the server challenges the client for credentials with a 401 - Access Denied response.
After calling this method, use send to send the request and data, if any, to the server.
Standards Information
This method is defined in
The XMLHttpRequest Object (W3C Working Draft) .
Applies To
See Also
abort, onreadystatechange, Communicating XML Data over the Web with WebDAV