XMLHttpRequest
Utilize os objetos XMLHttpRequest
(XHR) para interagir com os servidores. Pode obter os dados de um URL sem ter que recarregar toda a página. Isto permite que uma página da Web atualize apenas parte da mesma, sem interromper o que o utilizador está a fazer. XMLHttpRequest
é totalmente utilizado na programação Ajax.
História
XMLHttpRequest
was originally designed by Microsoft around 1999 and later adopted by Mozilla, Apple, and Google. Since October 2014, it has been standardized at the WHATWG, together with the new promise-based fetch()
(en-US) method.
Despite its name, XMLHttpRequest
can be used to retrieve any type of data, not just XML, and it supports protocols other than HTTP (including file
and ftp
).
Constructor
XMLHttpRequest()
(en-US)- The constructor initializes an XMLHttpRequest. It must be called before any other method calls.
Propriedades
This interface also inherits properties of XMLHttpRequestEventTarget
(en-US) and of EventTarget
(en-US).
XMLHttpRequest.onreadystatechange
(en-US)- An
EventHandler
(en-US) that is called whenever thereadyState
attribute changes. XMLHttpRequest.readyState
(en-US) Read only- Returns an
unsigned short
, the state of the request. XMLHttpRequest.response
(en-US) Read only- Returns an
ArrayBuffer
(en-US),Blob
,Document
, JavaScript object, or aDOMString
, depending on the value ofXMLHttpRequest.responseType
(en-US). that contains the response entity body. XMLHttpRequest.responseText
(en-US) Read only- Returns a
DOMString
that contains the response to the request as text, ornull
if the request was unsuccessful or has not yet been sent. XMLHttpRequest.responseType
(en-US)- Is an enumerated value that defines the response type.
XMLHttpRequest.responseURL
(en-US) Read only- Returns the serialized URL of the response or the empty string if the URL is null.
XMLHttpRequest.responseXML
(en-US) Read only- Returns a
Document
containing the response to the request, ornull
if the request was unsuccessful, has not yet been sent, or cannot be parsed as XML or HTML. Not available in workers. XMLHttpRequest.status
(en-US) Read only- Returns an
unsigned short
with the status of the response of the request. XMLHttpRequest.statusText
(en-US) Read only- Returns a
DOMString
containing the response string returned by the HTTP server. UnlikeXMLHTTPRequest.status
(en-US), this includes the entire text of the response message ("200 OK
", for example).
Nota: via HTTP/2 specification (8.1.2.4 Response Pseudo-Header Fields), HTTP/2 does not define a way to carry the version or reason phrase that is included in an HTTP/1.1 status line.
XMLHttpRequest.timeout
(en-US)- Is an
unsigned long
representing the number of milliseconds a request can take before automatically being terminated. XMLHttpRequestEventTarget.ontimeout
- Is an
EventHandler
(en-US) that is called whenever the request times out. XMLHttpRequest.upload
(en-US) Read only- Is an
XMLHttpRequestUpload
, representing the upload process. XMLHttpRequest.withCredentials
(en-US)- Is a
Boolean
(en-US) that indicates whether or not cross-siteAccess-Control
requests should be made using credentials such as cookies or authorization headers.
Proriedades não padrão
XMLHttpRequest.channel
(en-US)Read only- Is a
nsIChannel
. The channel used by the object when performing the request. XMLHttpRequest.mozAnon
(en-US)Read only- Is a boolean. If true, the request will be sent without cookie and authentication headers.
XMLHttpRequest.mozSystem
(en-US)Read only- Is a boolean. If true, the same origin policy will not be enforced on the request.
XMLHttpRequest.mozBackgroundRequest
(en-US)- Is a boolean. It indicates whether or not the object represents a background service request.
XMLHttpRequest.mozResponseArrayBuffer
(en-US) Obsolete since Gecko 6 Read only- Is an
ArrayBuffer
. The response to the request, as a JavaScript typed array. XMLHttpRequest.multipart
(en-US)Obsolete since Gecko 22- This Gecko-only feature, a boolean, was removed in Firefox/Gecko 22. Please use Server-Sent Events, Web Sockets, or
responseText
from progress events instead.
Manipuladores de evento
onreadystatechange
as a property of the XMLHttpRequest
instance is supported in all browsers.
Since then, a number of additional event handlers were implemented in various browsers (onload
, onerror
, onprogress
, etc.). These are supported in Firefox. In particular, see nsIXMLHttpRequestEventTarget
and Using XMLHttpRequest.
More recent browsers, including Firefox, also support listening to the XMLHttpRequest
events via standard addEventListener
APIs in addition to setting on*
properties to a handler function.
Métodos
XMLHttpRequest.abort()
(en-US)- Aborts the request if it has already been sent.
XMLHttpRequest.getAllResponseHeaders()
(en-US)- Returns all the response headers, separated by CRLF, as a string, or
null
if no response has been received. XMLHttpRequest.getResponseHeader()
(en-US)- Returns the string containing the text of the specified header, or
null
if either the response has not yet been received or the header doesn't exist in the response. XMLHttpRequest.open()
(en-US)- Initializes a request. This method is to be used from JavaScript code; to initialize a request from native code, use
openRequest()
instead. XMLHttpRequest.overrideMimeType()
(en-US)- Overrides the MIME type returned by the server.
XMLHttpRequest.send()
(en-US)- Sends the request. If the request is asynchronous (which is the default), this method returns as soon as the request is sent.
XMLHttpRequest.setRequestHeader()
(en-US)- Sets the value of an HTTP request header. You must call
setRequestHeader()
afteropen()
, but beforesend()
.
Métodos não padrão
XMLHttpRequest.init()
- Initializes the object for use from C++ code.
XMLHttpRequest.openRequest()
- Initializes a request. This method is to be used from native code; to initialize a request from JavaScript code, use
open()
instead. See the documentation foropen()
. XMLHttpRequest.sendAsBinary()
- A variant of the
send()
method that sends binary data.
Especificações
Especificação | Estado | Comentário |
---|---|---|
XMLHttpRequest | Living Standard | Live standard, latest version |
Compatibilidade de navegador
BCD tables only load in the browser
Consulte também
- Tutoriais da MDN abrangendo XMLHttpRequest:
- HTML5 Rocks — New Tricks in XMLHttpRequest2
Chrome scope availability
— how to access XMLHttpRequest from JSM modules etc., which do not have access to DOM