dart:html

HttpRequest class

A client-side XHR request for getting data from a URL, formally known as XMLHttpRequest.

HttpRequest can be used to obtain data from HTTP and FTP protocols, and is useful for AJAX-style page updates.

The simplest way to get the contents of a text file, such as a JSON-formatted file, is with getString. For example, the following code gets the contents of a JSON file and prints its length:

var path = 'myData.json';
HttpRequest.getString(path).then((String fileContents) {
  print(fileContents.length);
}).catchError((error) {
  print(error.toString());
});

Fetching data from other servers

For security reasons, browsers impose restrictions on requests made by embedded apps. With the default behavior of this class, the code making the request must be served from the same origin (domain name, port, and application layer protocol) as the requested resource. In the example above, the myData.json file must be co-located with the app that uses it.

Other resources

• Fetch data dynamically, a tutorial shows how to load data from a static file or from a server.
• Dart article on using HttpRequests
• JS XMLHttpRequest
• Using XMLHttpRequest

Inheritance

• Object
• EventTarget
• HttpRequestEventTarget
• HttpRequest

Annotations

• @Native("XMLHttpRequest")

Constructors

HttpRequest()

factory

General constructor for any type of request (GET, POST, etc). [...]

Properties

hashCode → int

read-only, inherited

The hash code for this object. [...]

on → Events

read-only, inherited

This is an ease-of-use accessor for event streams which should only be used when an explicit accessor is not available.

onAbort → Stream<ProgressEvent>

read-only, inherited

Stream of abort events handled by this HttpRequestEventTarget.

onError → Stream<ProgressEvent>

read-only, inherited

Stream of error events handled by this HttpRequestEventTarget.

onLoad → Stream<ProgressEvent>

read-only, inherited

Stream of load events handled by this HttpRequestEventTarget.

onLoadEnd → Stream<ProgressEvent>

@SupportedBrowser(SupportedBrowser.CHROME), @SupportedBrowser(SupportedBrowser.FIREFOX), @SupportedBrowser(SupportedBrowser.IE, '10'), @SupportedBrowser(SupportedBrowser.SAFARI), read-only, inherited

Stream of loadend events handled by this HttpRequestEventTarget.

onLoadStart → Stream<ProgressEvent>

read-only, inherited

Stream of loadstart events handled by this HttpRequestEventTarget.

onProgress → Stream<ProgressEvent>

@SupportedBrowser(SupportedBrowser.CHROME), @SupportedBrowser(SupportedBrowser.FIREFOX), @SupportedBrowser(SupportedBrowser.IE, '10'), @SupportedBrowser(SupportedBrowser.SAFARI), read-only, inherited

Stream of progress events handled by this HttpRequestEventTarget.

onReadyStateChange → Stream<Event>

read-only

Event listeners to be notified every time the HttpRequest object's readyState changes values.

onTimeout → Stream<ProgressEvent>

read-only, inherited

Stream of timeout events handled by this HttpRequestEventTarget.

readyState → int

read-only

Indicator of the current state of the request: [...]

response → dynamic

@SupportedBrowser(SupportedBrowser.CHROME), @SupportedBrowser(SupportedBrowser.FIREFOX), @SupportedBrowser(SupportedBrowser.IE, '10'), @SupportedBrowser(SupportedBrowser.SAFARI), read-only

The data received as a reponse from the request. [...]

responseHeaders → Map<String, String>

read-only

Returns all response headers as a key-value map. [...]

responseText → String?

read-only

The response in String form or empty String on failure.

responseType ↔ String

read / write

String telling the server the desired response format. [...]

responseUrl → String?

@JSName('responseURL'), read-only

responseXml → Document?

@JSName('responseXML'), read-only

The request response, or null on failure. [...]

runtimeType → Type

read-only, inherited

A representation of the runtime type of the object.

status → int?

read-only

The HTTP result code from the request (200, 404, etc). See also: HTTP Status Codes

statusText → String?

read-only

The request response string (such as "OK"). See also: HTTP Status Codes

timeout ↔ int?

read / write

Length of time in milliseconds before a request is automatically terminated. [...]

upload → HttpRequestUpload

@Unstable(), read-only

EventTarget that can hold listeners to track the progress of the request. The events fired will be members of HttpRequestUploadEvents.

withCredentials ↔ bool?

read / write

True if cross-site requests should use credentials such as cookies or authorization headers; false otherwise. [...]

Methods

abort() → void

Stop the current request. [...]

addEventListener(String type, EventListener? listener, [bool? useCapture]) → void

inherited

dispatchEvent(Event event) → bool

inherited

getAllResponseHeaders() → String

@Unstable()

Retrieve all the response headers from a request. [...]

getResponseHeader(String name) → String?

@Unstable()

Return the response header named header, or null if not found. [...]

noSuchMethod(Invocation invocation) → dynamic

inherited

Invoked when a non-existent method or property is accessed. [...]

open(String method, String url, {bool? async, String? user, String? password}) → void

Specify the desired url, and method to use in making the request. [...]

overrideMimeType(String mime) → void

@SupportedBrowser(SupportedBrowser.CHROME), @SupportedBrowser(SupportedBrowser.FIREFOX), @SupportedBrowser(SupportedBrowser.SAFARI)

Specify a particular MIME type (such as text/xml) desired for the response. [...]

removeEventListener(String type, EventListener? listener, [bool? useCapture]) → void

inherited

send([dynamic body_OR_data]) → void

Send the request with any given data. [...]

setRequestHeader(String name, String value) → void

Sets the value of an HTTP request header. [...]

toString() → String

inherited

A string representation of this object. [...]

Operators

operator ==(Object other) → bool

inherited

The equality operator. [...]

Static Properties

supportsCrossOrigin → bool

read-only

Checks to see if the current platform supports making cross origin requests. [...]

supportsLoadEndEvent → bool

read-only

Checks to see if the LoadEnd event is supported on the current platform.

supportsOverrideMimeType → bool

read-only

Checks to see if the overrideMimeType method is supported on the current platform.

supportsProgressEvent → bool

read-only

Checks to see if the Progress event is supported on the current platform.

Static Methods

getString(String url, {bool? withCredentials, void onProgress(ProgressEvent e)}) → Future<String>

Creates a GET request for the specified url. [...]

postFormData(String url, Map<String, String> data, {bool? withCredentials, String? responseType, Map<String, String>? requestHeaders, void onProgress(ProgressEvent e)}) → Future<HttpRequest>

Makes a server POST request with the specified data encoded as form data. [...]

request(String url, {String? method, bool? withCredentials, String? responseType, String? mimeType, Map<String, String>? requestHeaders, dynamic sendData, void onProgress(ProgressEvent e)}) → Future<HttpRequest>

Creates and sends a URL request for the specified url. [...]

requestCrossOrigin(String url, {String? method, String? sendData}) → Future<String>

Makes a cross-origin request to the specified URL. [...]

Constants

DONE → const int

4

HEADERS_RECEIVED → const int

2

LOADING → const int

3

OPENED → const int

1

readyStateChangeEvent → const EventStreamProvider<Event>

Static factory designed to expose readystatechange events to event handlers that are not necessarily instances of HttpRequest. [...]

const EventStreamProvider<Event>('readystatechange')

UNSENT → const int

0