Interface WebSocket

Provides the API for creating and managing a WebSocket connection to a server, as well as for sending and receiving data on the connection.

MDN Reference

interface WebSocket {
    CLOSED: 3;
    CLOSING: 2;
    CONNECTING: 0;
    OPEN: 1;
    binaryType: BinaryType;
    bufferedAmount: number;
    extensions: string;
    onclose: null | ((this, ev) => any);
    onerror: null | ((this, ev) => any);
    onmessage: null | ((this, ev) => any);
    onopen: null | ((this, ev) => any);
    protocol: string;
    readyState: number;
    url: string;
    addEventListener<K>(type, listener, options?): void;
    addEventListener(type, listener, options?): void;
    close(code?, reason?): void;
    dispatchEvent(event): boolean;
    removeEventListener<K>(type, listener, options?): void;
    removeEventListener(type, listener, options?): void;
    send(data): void;
}

Hierarchy (view full)

Properties

CLOSED CLOSING CONNECTING OPEN binaryType bufferedAmount extensions onclose onerror onmessage onopen protocol readyState url

Methods

addEventListener close dispatchEvent removeEventListener send

Properties

Readonly CLOSED

CLOSED: 3

Readonly CLOSING

CLOSING: 2

Readonly CONNECTING

CONNECTING: 0

Readonly OPEN

OPEN: 1

binaryType

binaryType: BinaryType

Returns a string that indicates how binary data from the WebSocket object is exposed to scripts:

Can be set, to change how binary data is returned. The default is "blob".

MDN Reference

Readonly bufferedAmount

bufferedAmount: number

Returns the number of bytes of application data (UTF-8 text and binary data) that have been queued using send() but not yet been transmitted to the network.

If the WebSocket connection is closed, this attribute's value will only increase with each call to the send() method. (The number does not reset to zero once the connection closes.)

MDN Reference

Readonly extensions

extensions: string

Returns the extensions selected by the server, if any.

MDN Reference

onclose

onclose: null | ((this, ev) => any)

MDN Reference

Type declaration

onerror

onerror: null | ((this, ev) => any)

MDN Reference

Type declaration

onmessage

onmessage: null | ((this, ev) => any)

MDN Reference

Type declaration

    • (this, ev): any

    • Parameters

      Returns any

onopen

onopen: null | ((this, ev) => any)

MDN Reference

Type declaration

Readonly protocol

protocol: string

Returns the subprotocol selected by the server, if any. It can be used in conjunction with the array form of the constructor's second argument to perform subprotocol negotiation.

MDN Reference

Readonly readyState

readyState: number

Returns the state of the WebSocket object's connection. It can have the values described below.

MDN Reference

Readonly url

url: string

Returns the URL that was used to establish the WebSocket connection.

MDN Reference

Methods

addEventListener

  • addEventListener<K>(type, listener, options?): void

  • Appends an event listener for events whose type attribute value is type. The callback argument sets the callback that will be invoked when the event is dispatched.

    The options argument sets listener-specific options. For compatibility this can be a boolean, in which case the method behaves exactly as if the value was specified as options's capture.

    When set to true, options's capture prevents callback from being invoked when the event's eventPhase attribute value is BUBBLING_PHASE. When false (or not present), callback will not be invoked when event's eventPhase attribute value is CAPTURING_PHASE. Either way, callback will be invoked if event's eventPhase attribute value is AT_TARGET.

    When set to true, options's passive indicates that the callback will not cancel the event by invoking preventDefault(). This is used to enable performance optimizations described in § 2.8 Observing event listeners.

    When set to true, options's once indicates that the callback will only be invoked once after which the event listener will be removed.

    If an AbortSignal is passed for options's signal, then the event listener will be removed when signal is aborted.

    The event listener is appended to target's event listener list and is not appended if it has the same type, callback, and capture.

    MDN Reference

    Type Parameters

    Parameters

    Returns void

  • addEventListener(type, listener, options?): void

  • Parameters

    Returns void

close

  • close(code?, reason?): void

  • Closes the WebSocket connection, optionally using code as the the WebSocket connection close code and reason as the the WebSocket connection close reason.

    MDN Reference

    Parameters

    • Optional code: number
    • Optional reason: string

    Returns void

dispatchEvent

  • dispatchEvent(event): boolean

  • Dispatches a synthetic event event to target and returns true if either event's cancelable attribute value is false or its preventDefault() method was not invoked, and false otherwise.

    MDN Reference

    Parameters

    Returns boolean

removeEventListener

send

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