XMLHttpRequest: open() method
The XMLHttpRequest
method open()
initializes a newly-created request, or re-initializes an existing one.
Note: Calling this method for an already active request
(one for which open()
has already been called) is the equivalent of calling
abort()
.
Syntax
js
open(method, url)
open(method, url, async)
open(method, url, async, user)
open(method, url, async, user, password)
Parameters
method
-
The HTTP request method to use, such as
"GET"
,"POST"
,"PUT"
,"DELETE"
, etc. Ignored for non-HTTP(S) URLs. url
-
A string representing the URL to send the request to.
async
Optional-
An optional Boolean parameter, defaulting to
true
, indicating whether or not to perform the operation asynchronously. If this value isfalse
, thesend()
method does not return until the response is received. Iftrue
, notification of a completed transaction is provided using event listeners. This must be true if themultipart
attribute istrue
, or an exception will be thrown.Note: Synchronous requests on the main thread can be easily disruptive to the user experience and should be avoided; in fact, many browsers have deprecated synchronous XHR support on the main thread entirely. Synchronous requests are permitted in
Worker
s. user
Optional-
The optional user name to use for authentication purposes; by default, this is the
null
value. password
Optional-
The optional password to use for authentication purposes; by default, this is the
null
value.
Return value
None (undefined
).
Specifications
Specification |
---|
XMLHttpRequest Standard # the-open()-method |
Browser compatibility
BCD tables only load in the browser
See also
- Using XMLHttpRequest
-
Related
XMLHttpRequest
methods:setRequestHeader()
,send()
, andabort()