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
XMLHttpRequest.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
DOMString
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 inWorker
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.
Specifications
Specification | Status | Comment |
---|---|---|
XMLHttpRequest The definition of 'open()' in that specification. |
Living Standard | WHATWG living standard |
Browser compatibility
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
open | Chrome Full support 1 | Edge Full support 12 | Firefox
Full support
1
| IE Full support 5 | Opera Full support 8 | Safari Full support 1.2 | WebView Android Full support 1 | Chrome Android Full support 18 | Firefox Android
Full support
4
| Opera Android Full support 10.1 | Safari iOS Full support 1 | Samsung Internet Android Full support 1.0 |
Legend
- Full support
- Full support
- See implementation notes.
- See implementation notes.
See also
- Using XMLHttpRequest
- Related
XMLHttpRequest
methods:setRequestHeader()
,send()
, andabort()