XMLHttpRequest.open()

The XMLHttpRequest.open() method initializes a request. This method is to be used from JavaScript code; to initialize a request from native code, use openRequest() instead.

void open(
   DOMString <var>method</var>,
   DOMString <var>url</var>,
   optional boolean <var>async</var>,
   optional DOMString <var>user</var>,
   optional DOMString <var>password</var>
);

Parameters

method

The HTTP method to use, such as "GET", "POST", "PUT", "DELETE", etc. Ignored for non-HTTP(S) URLs.

url

The URL to send the request to.

async

An optional boolean parameter, defaulting to true, indicating whether or not to perform the operation asynchronously. If this value is false, the 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 multipart attribute is true, or an exception will be thrown.

Note: Starting with Gecko 30.0 (Firefox 30.0 / Thunderbird 30.0 / SeaMonkey 2.27), synchronous requests on the main thread have been deprecated due to the negative effects to the user experience.

user

The optional user name to use for authentication purposes; by default, this is an empty string.

password

The optional password to use for authentication purposes; by default, this is an empty string.

Specifications

Specification	Status	Comment
XMLHttpRequest The definition of 'open()' in that specification.	Living Standard	WHATWG living standard

Browser compatibility

• Desktop
• Mobile

Feature	Chrome	Firefox (Gecko)	Internet Explorer	Opera	Safari (WebKit)
Basic support	1	(Yes)	5[1] 7	(Yes)	1.2

Feature	Android	Chrome for Android	Firefox Mobile (Gecko)	IE Mobile	Opera Mobile	Safari Mobile
Basic support	(Yes)	1.0	(Yes)	(Yes)	(Yes)	(Yes)

[1] This feature was implemented via ActiveXObject(). Internet Explorer implements the standard XMLHttpRequest since version 7.

See also

Using XMLHttpRequest