version added: 1.5jQuery.ajax( url [, settings ] )
- urlType: StringA string containing the URL to which the request is sent.
- settingsType: PlainObjectA set of key/value pairs that configure the Ajax request. All settings are optional. A default can be set for any option with $.ajaxSetup(). See jQuery.ajax( settings ) below for a complete list of all settings.
version added: 1.0jQuery.ajax( [settings ] )
- settingsType: PlainObjectA set of key/value pairs that configure the Ajax request. All settings are optional. A default can be set for any option with $.ajaxSetup().
- accepts (default:
depends on DataType
)Type: PlainObjectThe content type sent in the request header that tells the server what kind of response it will accept in return. If theaccepts
setting needs modification, it is recommended to do so once in the$.ajaxSetup()
method. - async (default:
true
)Type: BooleanBy default, all requests are sent asynchronously (i.e. this is set totrue
by default). If you need synchronous requests, set this option tofalse
. Cross-domain requests anddataType: "jsonp"
requests do not support synchronous operation. Note that synchronous requests may temporarily lock the browser, disabling any actions while the request is active. As of jQuery 1.8, the use ofasync: false
with jqXHR ($.Deferred
) is deprecated; you must use the success/error/complete callback options instead of the corresponding methods of the jqXHR object such asjqXHR.done()
or the deprecatedjqXHR.success()
. - beforeSendType: Function( jqXHR jqXHR, PlainObject settings )A pre-request callback function that can be used to modify the jqXHR (in jQuery 1.4.x, XMLHTTPRequest) object before it is sent. Use this to set custom headers, etc. The jqXHR and settings objects are passed as arguments. This is an Ajax Event. Returning
false
in thebeforeSend
function will cancel the request. As of jQuery 1.5, thebeforeSend
option will be called regardless of the type of request. - cache (default:
true, false for dataType 'script' and 'jsonp'
)Type: BooleanIf set tofalse
, it will force requested pages not to be cached by the browser. Note: Settingcache
to false will only work correctly with HEAD and GET requests. It works by appending "_={timestamp}" to the GET parameters. The parameter is not needed for other types of requests, except in IE8 when a POST is made to a URL that has already been requested by a GET. - completeType: Function( jqXHR jqXHR, String textStatus )A function to be called when the request finishes (after
success
anderror
callbacks are executed). The function gets passed two arguments: The jqXHR (in jQuery 1.4.x, XMLHTTPRequest) object and a string categorizing the status of the request ("success"
,"notmodified"
,"error"
,"timeout"
,"abort"
, or"parsererror"
). As of jQuery 1.5, thecomplete
setting can accept an array of functions. Each function will be called in turn. This is an Ajax Event. - contentsType: PlainObjectAn object of string/regular-expression pairs that determine how jQuery will parse the response, given its content type. (version added: 1.5)
- contentType (default:
'application/x-www-form-urlencoded; charset=UTF-8'
)Type: StringWhen sending data to the server, use this content type. Default is "application/x-www-form-urlencoded; charset=UTF-8", which is fine for most cases. If you explicitly pass in a content-type to$.ajax()
, then it is always sent to the server (even if no data is sent). The W3C XMLHttpRequest specification dictates that the charset is always UTF-8; specifying another charset will not force the browser to change the encoding. - contextType: PlainObjectThis object will be made the context of all Ajax-related callbacks. By default, the context is an object that represents the ajax settings used in the call (
$.ajaxSettings
merged with the settings passed to$.ajax
). For example, specifying a DOM element as the context will make that the context for thecomplete
callback of a request, like so:123456$.ajax({
url: "test.html",
context: document.body
}).done(function() {
$( this ).addClass( "done" );
});
- converters (default:
{"* text": window.String, "text html": true, "text json": jQuery.parseJSON, "text xml": jQuery.parseXML}
)Type: PlainObjectAn object containing dataType-to-dataType converters. Each converter's value is a function that returns the transformed value of the response. (version added: 1.5) - crossDomain (default:
false for same-domain requests, true for cross-domain requests
)Type: BooleanIf you wish to force a crossDomain request (such as JSONP) on the same domain, set the value of crossDomain totrue
. This allows, for example, server-side redirection to another domain. (version added: 1.5) - dataType: PlainObject or StringData to be sent to the server. It is converted to a query string, if not already a string. It's appended to the url for GET-requests. See
processData
option to prevent this automatic processing. Object must be Key/Value pairs. If value is an Array, jQuery serializes multiple values with same key based on the value of thetraditional
setting (described below). - dataFilterType: Function( String data, String type ) => ObjectA function to be used to handle the raw response data of XMLHttpRequest.This is a pre-filtering function to sanitize the response. You should return the sanitized data. The function accepts two arguments: The raw data returned from the server and the 'dataType' parameter.
- dataType (default:
Intelligent Guess (xml, json, script, or html)
)Type: StringThe type of data that you're expecting back from the server. If none is specified, jQuery will try to infer it based on the MIME type of the response (an XML MIME type will yield XML, in 1.4 JSON will yield a JavaScript object, in 1.4 script will execute the script, and anything else will be returned as a string). The available types (and the result passed as the first argument to your success callback) are:- "xml": Returns a XML document that can be processed via jQuery.
- "html": Returns HTML as plain text; included script tags are evaluated when inserted in the DOM.
- "script": Evaluates the response as JavaScript and returns it as plain text. Disables caching by appending a query string parameter, "_=[TIMESTAMP]", to the URL unless the
cache
option is set totrue
. Note: This will turn POSTs into GETs for remote-domain requests. - "json": Evaluates the response as JSON and returns a JavaScript object. The JSON data is parsed in a strict manner; any malformed JSON is rejected and a parse error is thrown. As of jQuery 1.9, an empty response is also rejected; the server should return a response of
null
or{}
instead. (See json.org for more information on proper JSON formatting.) - "jsonp": Loads in a JSON block using JSONP. Adds an extra "?callback=?" to the end of your URL to specify the callback. Disables caching by appending a query string parameter, "_=[TIMESTAMP]", to the URL unless the
cache
option is set totrue
. - "text": A plain text string.
- multiple, space-separated values: As of jQuery 1.5, jQuery can convert a dataType from what it received in the Content-Type header to what you require. For example, if you want a text response to be treated as XML, use "text xml" for the dataType. You can also make a JSONP request, have it received as text, and interpreted by jQuery as XML: "jsonp text xml." Similarly, a shorthand string such as "jsonp xml" will first attempt to convert from jsonp to xml, and, failing that, convert from jsonp to text, and then from text to xml.
- errorType: Function( jqXHR jqXHR, String textStatus, String errorThrown )A function to be called if the request fails. The function receives three arguments: The jqXHR (in jQuery 1.4.x, XMLHttpRequest) object, a string describing the type of error that occurred and an optional exception object, if one occurred. Possible values for the second argument (besides
null
) are"timeout"
,"error"
,"abort"
, and"parsererror"
. When an HTTP error occurs,errorThrown
receives the textual portion of the HTTP status, such as "Not Found" or "Internal Server Error." As of jQuery 1.5, theerror
setting can accept an array of functions. Each function will be called in turn.Note: This handler is not called for cross-domain script and cross-domain JSONP requests. This is anAjax Event. - global (default:
true
)Type: BooleanWhether to trigger global Ajax event handlers for this request. The default istrue
. Set tofalse
to prevent the global handlers likeajaxStart
orajaxStop
from being triggered. This can be used to control various Ajax Events. - headers (default:
{}
)Type: PlainObjectAn object of additional header key/value pairs to send along with requests using the XMLHttpRequest transport. The headerX-Requested-With: XMLHttpRequest
is always added, but its defaultXMLHttpRequest
value can be changed here. Values in theheaders
setting can also be overwritten from within thebeforeSend
function. (version added: 1.5) - ifModified (default:
false
)Type: BooleanAllow the request to be successful only if the response has changed since the last request. This is done by checking the Last-Modified header. Default value isfalse
, ignoring the header. In jQuery 1.4 this technique also checks the 'etag' specified by the server to catch unmodified data. - isLocal (default:
depends on current location protocol
)Type: BooleanAllow the current environment to be recognized as "local," (e.g. the filesystem), even if jQuery does not recognize it as such by default. The following protocols are currently recognized as local:file
,*-extension
, andwidget
. If theisLocal
setting needs modification, it is recommended to do so once in the$.ajaxSetup()
method. (version added: 1.5.1) - jsonpType: StringOverride the callback function name in a jsonp request. This value will be used instead of 'callback' in the 'callback=?' part of the query string in the url. So
{jsonp:'onJSONPLoad'}
would result in'onJSONPLoad=?'
passed to the server. As of jQuery 1.5, setting thejsonp
option tofalse
prevents jQuery from adding the "?callback" string to the URL or attempting to use "=?" for transformation. In this case, you should also explicitly set thejsonpCallback
setting. For example,{ jsonp: false, jsonpCallback: "callbackName" }
- jsonpCallbackType: String or Function()Specify the callback function name for a JSONP request. This value will be used instead of the random name automatically generated by jQuery. It is preferable to let jQuery generate a unique name as it'll make it easier to manage the requests and provide callbacks and error handling. You may want to specify the callback when you want to enable better browser caching of GET requests. As of jQuery 1.5, you can also use a function for this setting, in which case the value of
jsonpCallback
is set to the return value of that function. - mimeTypeType: StringA mime type to override the XHR mime type. (version added: 1.5.1)
- passwordType: StringA password to be used with XMLHttpRequest in response to an HTTP access authentication request.
- processData (default:
true
)Type: BooleanBy default, data passed in to the data option as an object (technically, anything other than a string) will be processed and transformed into a query string, fitting to the default content-type "application/x-www-form-urlencoded". If you want to send a DOMDocument, or other non-processed data, set this option tofalse
. - scriptCharsetType: StringOnly applies when the "script" transport is used (e.g., cross-domain requests with "jsonp" or "script" dataType and "GET" type). Sets the
charset
attribute on the script tag used in the request. Used when the character set on the local page is not the same as the one on the remote script. - statusCode (default:
{}
)Type: PlainObjectAn object of numeric HTTP codes and functions to be called when the response has the corresponding code. For example, the following will alert when the response status is a 404:1234567$.ajax({
statusCode: {
404: function() {
alert( "page not found" );
}
}
});
If the request is successful, the status code functions take the same parameters as the success callback; if it results in an error (including 3xx redirect), they take the same parameters as the(version added: 1.5)error
callback. - successType: Function( PlainObject data, String textStatus, jqXHR jqXHR )A function to be called if the request succeeds. The function gets passed three arguments: The data returned from the server, formatted according to the
dataType
parameter; a string describing the status; and thejqXHR
(in jQuery 1.4.x, XMLHttpRequest) object. As of jQuery 1.5, the success setting can accept an array of functions. Each function will be called in turn. This is an Ajax Event. - timeoutType: NumberSet a timeout (in milliseconds) for the request. This will override any global timeout set with$.ajaxSetup(). The timeout period starts at the point the
$.ajax
call is made; if several other requests are in progress and the browser has no connections available, it is possible for a request to time out before it can be sent. In jQuery 1.4.x and below, the XMLHttpRequest object will be in an invalid state if the request times out; accessing any object members may throw an exception. In Firefox 3.0+ only,script and JSONP requests cannot be cancelled by a timeout; the script will run even if it arrives after the timeout period. - traditionalType: BooleanSet this to
true
if you wish to use the traditional style of param serialization. - type (default:
'GET'
)Type: StringThe type of request to make ("POST" or "GET"), default is "GET". Note: Other HTTP request methods, such as PUT and DELETE, can also be used here, but they are not supported by all browsers. - url (default:
The current page
)Type: StringA string containing the URL to which the request is sent. - usernameType: StringA username to be used with XMLHttpRequest in response to an HTTP access authentication request.
- xhr (default:
ActiveXObject when available (IE), the XMLHttpRequest otherwise
)Type: Function()Callback for creating the XMLHttpRequest object. Defaults to the ActiveXObject when available (IE), the XMLHttpRequest otherwise. Override to provide your own implementation for XMLHttpRequest or enhancements to the factory. - xhrFieldsType: PlainObjectAn object of fieldName-fieldValue pairs to set on the native
XHR
object. For example, you can use it to setwithCredentials
totrue
for cross-domain requests if needed.123456$.ajax({
url: a_cross_domain_url,
xhrFields: {
withCredentials: true
}
});
In jQuery 1.5, the(version added: 1.5.1)withCredentials
property was not propagated to the nativeXHR
and thus CORS requests requiring it would ignore this flag. For this reason, we recommend using jQuery 1.5.1+ should you require the use of it.
$.ajax()
function underlies all Ajax requests sent by jQuery. It is often unnecessary to directly call this function, as several higher-level alternatives like $.get()
and .load()
are available and are easier to use. If less common options are required, though, $.ajax()
can be used more flexibly.$.ajax()
function can be called with no arguments:
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$.ajaxSetup()
function.The jqXHR Object
$.ajax()
as of jQuery 1.5 is a superset of the browser's native XMLHttpRequest object. For example, it contains responseText
and responseXML
properties, as well as agetResponseHeader()
method. When the transport mechanism is something other than XMLHttpRequest (for example, a script tag for a JSONP request) the jqXHR
object simulates native XHR functionality where possible.jqXHR
object also contains the overrideMimeType()
method (it was available in jQuery 1.4.x, as well, but was temporarily removed in jQuery 1.5). The .overrideMimeType()
method may be used in the beforeSend()
callback function, for example, to modify the response content-type header:
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$.ajax()
as of jQuery 1.5 implement the Promise interface, giving them all the properties, methods, and behavior of a Promise (see Deferred object for more information). These methods take one or more function arguments that are called when the $.ajax()
request terminates. This allows you to assign multiple callbacks on a single request, and even to assign callbacks after the request may have completed. (If the request is already complete, the callback is fired immediately.) Available Promise methods of the jqXHR object include:- jqXHR.done(function( data, textStatus, jqXHR ) {});An alternative construct to the success callback option, the
.done()
method replaces the deprecatedjqXHR.success()
method. Refer todeferred.done()
for implementation details. - jqXHR.fail(function( jqXHR, textStatus, errorThrown ) {});An alternative construct to the error callback option, the
.fail()
method replaces the deprecated.error()
method. Refer todeferred.fail()
for implementation details. - jqXHR.always(function( data|jqXHR, textStatus, jqXHR|errorThrown ) { });An alternative construct to the complete callback option, the
.always()
method replaces the deprecated.complete()
method.In response to a successful request, the function's arguments are the same as those of.done()
: data, textStatus, and the jqXHR object. For failed requests the arguments are the same as those of.fail()
: the jqXHR object, textStatus, and errorThrown. Refer todeferred.always()
for implementation details. - jqXHR.then(function( data, textStatus, jqXHR ) {}, function( jqXHR, textStatus, errorThrown ) {});Incorporates the functionality of the
.done()
and.fail()
methods, allowing (as of jQuery 1.8) the underlying Promise to be manipulated. Refer todeferred.then()
for implementation details.
jqXHR.success()
, jqXHR.error()
, and jqXHR.complete()
callbacks are deprecated as of jQuery 1.8. To prepare your code for their eventual removal, use jqXHR.done()
, jqXHR.fail()
, andjqXHR.always()
instead.
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this
reference within all callbacks is the object in the context
option passed to $.ajax
in the settings; if context
is not specified, this
is a reference to the Ajax settings themselves.XMLHttpRequest
, a jqXHR
object will expose the following properties and methods:readyState
status
statusText
responseXML
and/orresponseText
when the underlying request responded with xml and/or text, respectivelysetRequestHeader(name, value)
which departs from the standard by replacing the old value with the new one rather than concatenating the new value to the old onegetAllResponseHeaders()
getResponseHeader()
statusCode()
abort()
onreadystatechange
mechanism is provided, however, since done
, fail
, always
, and statusCode
cover all conceivable requirements.Callback Function Queues
beforeSend
, error
, dataFilter
, success
and complete
options all accept callback functions that are invoked at the appropriate times.fail
and done
, and, as of jQuery 1.6, always
callback hooks are first-in, first-out managed queues, allowing for more than one callback for each hook. See Deferred object methods, which are implemented internally for these$.ajax()
callback hooks.$.ajax()
are as follows:beforeSend
callback option is invoked; it receives thejqXHR
object and thesettings
object as parameters.error
callback option is invoked, if the request fails. It receives thejqXHR
, a string indicating the error type, and an exception object if applicable. Some built-in errors will provide a string as the exception object: "abort", "timeout", "No Transport".dataFilter
callback option is invoked immediately upon successful receipt of response data. It receives the returned data and the value ofdataType
, and must return the (possibly altered) data to pass on tosuccess
.success
callback option is invoked, if the request succeeds. It receives the returned data, a string containing the success code, and thejqXHR
object.- Promise callbacks —
.done()
,.fail()
,.always()
, and.then()
— are invoked, in the order they are registered. complete
callback option fires, when the request finishes, whether in failure or success. It receives thejqXHR
object, as well as a string containing the success or error code.
Data Types
$.ajax()
function relies on the server to provide information about the retrieved data. If the server reports the return data as XML, the result can be traversed using normal XML methods or jQuery's selectors. If another type is detected, such as HTML in the example above, the data is treated as text.dataType
option. Besides plain xml
, the dataType
can be html
,json
, jsonp
, script
, or text
.text
and xml
types return the data with no processing. The data is simply passed on to the success handler, either through the responseText
or responseXML
property of the jqXHR
object, respectively.dataType
. In particular, XML must be declared by the server as text/xml
or application/xml
for consistent results.html
is specified, any embedded JavaScript inside the retrieved data is executed before the HTML is returned as a string. Similarly, script
will execute the JavaScript that is pulled back from the server, then return nothing.json
type parses the fetched data file as a JavaScript object and returns the constructed object as the result data. To do so, it uses jQuery.parseJSON()
when the browser supports it; otherwise it uses a Function
constructor. Malformed JSON data will throw a parse error (see json.org for more information). JSON data is convenient for communicating structured data in a way that is concise and easy for JavaScript to parse. If the fetched data file exists on a remote server, specify thejsonp
type instead.jsonp
type appends a query string parameter of callback=?
to the URL. The server should prepend the JSON data with the callback name to form a valid JSONP response. We can specify a parameter name other than callback
with thejsonp
option to $.ajax()
.script
or jsonp
data types), the error
callbacks and global events will never be fired.Sending Data to the Server
type
option. This option affects how the contents of the data
option are sent to the server. POST data will always be transmitted to the server using UTF-8 charset, per the W3C XMLHTTPRequest standard.data
option can contain either a query string of the form key1=value1&key2=value2
, or an object of the form{key1: 'value1', key2: 'value2'}
. If the latter form is used, the data is converted into a query string usingjQuery.param()
before it is sent. This processing can be circumvented by setting processData
to false
. The processing might be undesirable if you wish to send an XML object to the server; in this case, change the contentType
option fromapplication/x-www-form-urlencoded
to a more appropriate MIME type.Advanced Options
global
option prevents handlers registered using .ajaxSend()
, .ajaxError()
, and similar methods from firing when this request would trigger them. This can be useful to, for example, suppress a loading indicator that was implemented with.ajaxSend()
if the requests are frequent and brief. With cross-domain script and JSONP requests, the global option is automatically set to false
. See the descriptions of these methods below for more details. See the descriptions of these methods below for more details.username
and password
options.$.ajaxSetup()
rather than being overridden for specific requests with the timeout
option.cache
to false
. To cause the request to report failure if the asset has not been modified since the last request, set ifModified
to true
.scriptCharset
allows the character set to be explicitly specified for requests that use a
tag (that is, a type ofscript
or jsonp
). This is useful if the script and host page have differing character sets.
The first letter in Ajax stands for "asynchronous," meaning that the operation occurs in parallel and the order of completion is not guaranteed. The async
option to $.ajax()
defaults to true
, indicating that code execution can continue after the request is made. Setting this option to false
(and thus making the call no longer asynchronous) is strongly discouraged, as it can cause the browser to become unresponsive.
The $.ajax()
function returns the XMLHttpRequest
object that it creates. Normally jQuery handles the creation of this object internally, but a custom function for manufacturing one can be specified using the xhr
option. The returned object can generally be discarded, but does provide a lower-level interface for observing and manipulating the request. In particular, calling.abort()
on the object will halt the request before it completes.
Extending Ajax
As of jQuery 1.5, jQuery's Ajax implementation includes prefilters, transports, and converters that allow you to extend Ajax with a great deal of flexibility.
Using Converters
$.ajax()
converters support mapping data types to other data types. If, however, you want to map a custom data type to a known type (e.g json
), you must add a correspondance between the response Content-Type and the actual data type using the contents
option:
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This extra object is necessary because the response Content-Types and data types never have a strict one-to-one correspondance (hence the regular expression).
To convert from a supported type (e.g text
, json
) to a custom data type and back again, use another pass-through converter:
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The above now allows passing from text
to mycustomtype
and then mycustomtype
to json
.
Additional Notes:
- Due to browser security restrictions, most "Ajax" requests are subject to the same origin policy; the request can not successfully retrieve data from a different domain, subdomain, or protocol.
- Script and JSONP requests are not subject to the same origin policy restrictions.
Examples:
Example: Save some data to the server and notify the user once it's complete.
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Example: Retrieve the latest version of an HTML page.
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Example: Send an xml document as data to the server. By setting the processData option to false
, the automatic conversion of data to strings is prevented.
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Example: Send an id as data to the server, save some data to the server, and notify the user once it's complete. If the request fails, alert the user.
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Example: Load and execute a JavaScript file.
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