WebSocket : EventTarget

WebSockets are a persistent connection to a server that allows sending and receiving data.

Spec:
https://html.spec.whatwg.org/multipage/web-sockets.html#the-websocket-interface

----
new WebSocket(url : String) : WebSocket

Constructs a new WebSocket connection to **url**.

<htmlexample>
<script>
  // Connect to a WebSocket that echos back the messages it receives.
  var ws = new WebSocket('wss://echo.websocket.org/');
  ws.onopen = function(e) {
    console.log('WebSocket Opened. Sending "Hello"');
    ws.send('Hello');
  };

  ws.onmessage = function(e) {
    console.log('Received:', e.data);
  };
</script>
</htmlexample>

----
new WebSocket(url : String, protocol : String) : WebSocket

Same as %%#new_WebSocket_String_Iterable|**new WebSocket(url, [protocol])**%%.

----
new WebSocket(url : String, protocols : Iterable<String>) : WebSocket


----
instance.url : String

The url passed to the WebSocket constructor.

<htmlexample>
<script>
  // Connect to a WebSocket that echos back the messages it receives.
  var ws = new WebSocket('wss://echo.websocket.org/');
  console.log(ws.url);
</script>
</htmlexample>

ReadOnly:
true

----
instance.readyState : Number

One of %%#CONNECTING|**WebSocket.CONNECTING**%%,
%%#OPEN|**WebSocket.OPEN**%%,
%%#CLOSING|**WebSocket.CLOSING**%%, or
%%#CLOSED|**WebSocket.CLOSED**%%.

<htmlexample>
<button>Close</button>
<script>
  // Connect to a WebSocket that echos back the messages it receives.
  var ws = new WebSocket('wss://echo.websocket.org/');

  var readyStateNames = {
    [WebSocket.CONNECTING]: 'CONNECTING',
    [WebSocket.OPEN]: 'OPEN',
    [WebSocket.CLOSING]: 'CLOSING',
    [WebSocket.CLOSED]: 'CLOSED',
  };

  var logReadyState = function() {
    console.log(readyStateNames[ws.readyState]);
  };

  logReadyState();
  ws.onopen = logReadyState;
  ws.onclose = logReadyState;
  document.querySelector('button').onclick = function() {
    ws.close();
    logReadyState();
  };
</script>
</htmlexample>

ReadOnly:
true

----
instance.bufferedAmount : Number

ReadOnly:
true

----
instance.extensions : String

ReadOnly:
true

----
instance.protocol : String

ReadOnly:
true

----
instance.binaryType : String

Set to either **'arraybuffer'** or **'blob'** to choose if the %%MessageEvent#data|MessageEvent.data%%
property will be an %%/ArrayBuffer|ArrayBuffer%% or a %%/Blob|Blob%% for binary
data received by the WebSocket.

<htmlexample>
<script>
  var testBinaryType = function(binaryType) {
    // Connect to a WebSocket that echos back the messages it receives.
    var ws = new WebSocket('wss://echo.websocket.org/');
    ws.binaryType = binaryType;
    ws.onopen = function(e) {
      ws.send(new Uint32Array([1, 2, 3]));
    };

    ws.onmessage = function(e) {
      // The type of the data will match the specified binaryType
      console.log(binaryType + ':', e.data);
    };
  };

  testBinaryType('arraybuffer');
  testBinaryType('blob');
</script>
</htmlexample>

----
prototype.close([code : Number, [reason : String]]) : undefined

Closes the WebSocket connection.

----
prototype.send(data : ArrayBuffer) : undefined

Sends **data** to the server.

----
prototype.send(data : ArrayBufferView) : undefined

Sends **data** to the server.

----
prototype.send(data : Blob) : undefined

Sends **data** to the server.

----
prototype.send(data : String) : undefined

Sends **data** to the server.

----
CONNECTING : Number

The value of %%#readyState|readyState%% after constructing the WebSocket and before
%%#onopen|onopen%% fires.

ReadOnly:
true

Value:
0

----
OPEN : Number

The value of %%#readyState|readyState%% after %%#onopen|onopen%% fires.

ReadOnly:
true

Value:
1

----
CLOSING : Number

The value of %%#readyState|readyState%% after calling %%#close|**close()**%% and before
%%#onclose|onclose%% fires.

ReadOnly:
true

Value:
2

----
CLOSED : Number

The value of %%#readyState|readyState%% after %%#onclose|onclose%% fires.

ReadOnly:
true

Value:
3

----
event.open : listener(event : Event) : undefined

----
event.error : listener(event : ErrorEvent) : undefined

----
event.close : listener(event : CloseEvent) : undefined

----
event.message : listener(event : MessageEvent) : undefined