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This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.
O objeto WebSocket provê uma API para criação e gerenciamento de uma conexão WebSocket com um servidor, bem como o envio e recebimento de dados através dessa conexão.
O construtor do WebSocket aceita um parâmetro obrigatório e um opcional:
WebSocket WebSocket( in DOMString url, in optional DOMString protocols ); WebSocket WebSocket( in DOMString url, in optional DOMString[] protocols );
url- A URL da devida conexão; esta deve ser a URL da qual o servidor WebSocket irá responder.
protocolsOptional- Um único protocolo em formato texto ou uma lista de textos de protocolo. Estes textos são usados para indicar sub-protocolos, assim então um único servidor pode implementar múltiplos sub-protocolos WebSocket (por exemplo, você pode querer um servidor capaz de manipular diferentes tipos de interações dependendo do protocolo especificado). se você não especificar um protocolo em texto, será assumido um texto vazio.
O construtor pode lançar exceções:
SECURITY_ERR- A porta a qual a conexão está sendo executada está bloqueada.
Visão Geral do método
void close(É opciaonal: unsigned long code, in optional DOMString reason); |
void send(in DOMString data); |
Atributos
| Attributo | Tipo | Descrição |
binaryType |
DOMString |
Uma string indica o tipo de dado binário que está sendo transmitido pela conexão. Este deve ser tanto "blob" se o objeto DOM |
bufferedAmount |
unsigned long |
O número de bites de dados que tem sid consultado usando chamadas para |
extensions |
DOMString |
The extensions selected by the server. This is currently only the empty string or a list of extensions as negotiated by the connection. |
onclose |
EventListener |
An event listener to be called when the WebSocket connection's readyState changes to CLOSED. The listener receives a CloseEvent named "close". |
onerror |
EventListener |
An event listener to be called when an error occurs. This is a simple event named "error". |
onmessage |
EventListener |
An event listener to be called when a message is received from the server. The listener receives a MessageEvent named "message". |
onopen |
EventListener |
An event listener to be called when the WebSocket connection's readyState changes to OPEN; this indicates that the connection is ready to send and receive data. The event is a simple one with the name "open". |
protocol |
DOMString |
A string indicating the name of the sub-protocol the server selected; this will be one of the strings specified in the protocols parameter when creating the WebSocket object. |
readyState |
unsigned short |
The current state of the connection; this is one of the Ready state constants. Read only. |
url |
DOMString |
The URL as resolved by the constructor. This is always an absolute URL. Read only. |
Constants
Ready state constants
These constants are used by the readyState attribute to describe the state of the WebSocket connection.
| Constant | Value | Description |
CONNECTING |
0 |
The connection is not yet open. |
OPEN |
1 |
The connection is open and ready to communicate. |
CLOSING |
2 |
The connection is in the process of closing. |
CLOSED |
3 |
The connection is closed or couldn't be opened. |
Methods
close()
Closes the WebSocket connection or connection attempt, if any. If the connection is already CLOSED, this method does nothing.
void close( in optional unsigned short code, in optional DOMString reason );
Parameters
codeOptional- A numeric value indicating the status code explaining why the connection is being closed. If this parameter is not specified, a default value of 1000 (indicating a normal "transaction complete" closure) is assumed. See the list of status codes on the
CloseEventpage for permitted values. reasonOptional- A human-readable string explaining why the connection is closing. This string must be no longer than 123 bytes of UTF-8 text (not characters).
Exceptions thrown
INVALID_ACCESS_ERR- An invalid
codewas specified. SYNTAX_ERR- The
reasonstring is too long or contains unpaired surrogates.
Note: In Gecko, this method didn't support any parameters prior to Gecko 8.0 (Firefox 8.0 / Thunderbird 8.0 / SeaMonkey 2.5).
send()
Transmits data to the server over the WebSocket connection.
void send( in DOMString data ); void send( in ArrayBuffer data ); void send( in Blob data );
Parameters
data- A text string to send to the server.
Exceptions thrown
INVALID_STATE_ERR- The connection is not currently
OPEN. SYNTAX_ERR- The data is a string that has unpaired surrogates.
Note: Gecko's implementation of the send() method differs somewhat from the specification in Gecko 6.0; Gecko returns a boolean indicating whether or not the connection is still open (and, by extension, that the data was successfully queued or transmitted); this is corrected in Gecko 8.0.
As of Gecko 11.0, support for ArrayBuffer is implemented but not Blob data types.
Specifications
| Specification | Status | Comment |
|---|---|---|
| The WebSocket API The definition of 'WebSocket' in that specification. |
Candidate Recommendation | Initial definition |
Browser compatibility
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|
| Basic support | (Yes) | 4.0 (2.0)[1] | (Yes) | (Yes) | ? |
| Sub-protocol support | ? | 6.0 (6.0) | ? | ? | ? |
| Feature | Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|
| Basic support | ? | 7.0 (7.0)[1] | ? | ? | ? |
| Sub-protocol support | ? | 7.0 (7.0) | ? | ? | ? |
[1] Starting in Gecko 6.0 (Firefox 6.0 / Thunderbird 6.0 / SeaMonkey 2.3), the constructor is prefixed; you will need to use MozWebSocket(): var mySocket = new MozWebSocket("http://www.example.com/socketserver");
The extensions attribute was not supported in Gecko until Gecko 8.0.
Prior to Gecko 11.0 (Firefox 11.0 / Thunderbird 11.0 / SeaMonkey 2.8), outbound messages sent using the send() method were limited to 16 MB. They can now be up to 2 GB in size.