open() initializes a newly-created request, or re-initializes an existing one.
open()has already been called) is the equivalent of calling
XMLHttpRequest.open(method, url) XMLHttpRequest.open(method, url, async) XMLHttpRequest.open(method, url, async, user) XMLHttpRequest.open(method, url, async, user, password)
- The HTTP request method to use, such as
"DELETE", etc. Ignored for non-HTTP(S) URLs.
DOMStringrepresenting the URL to send the request to.
- An optional Boolean parameter, defaulting to
true, indicating whether or not to perform the operation asynchronously. If this value is
send()method does not return until the response is received. If
true, notification of a completed transaction is provided using event listeners. This must be true if the
true, 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
- The optional user name to use for authentication purposes; by default, this is the
- The optional password to use for authentication purposes; by default, this is the
The definition of 'open()' in that specification.
|Living Standard||WHATWG living standard|
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.
|Feature||Android webview||Chrome for Android||Edge mobile||Firefox for Android||Opera Android||iOS Safari||Samsung Internet|
1. Starting in Firefox 30, synchronous requests on the main thread have been deprecated due to their negative impact on performance and the user experience. Therefore, the
async parameter may not be
false except in a
2. Implemented via