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This article mainly introduces "how to use WebSocket API". In daily operation, I believe many people have doubts about how to use WebSocket API. The editor consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful to answer the doubts about "how to use WebSocket API". Next, please follow the editor to study!

Attribute

WebSocket has two properties, readyState and bufferedAmount, where bufferedAmount is used as connection buffering, and the readyState of the WebSocket service has the following four states.

 CONNECTING (value is the number 0). Indicates that the connection is in progress, but the connection has not been successful. There is a handshake process for network communication.

Note that at the beginning of any connection, its state must be CONNECTING=0. If the ready-State has been in the CONNECTING state, an INVALID_STATE_ERR exception will be reported.

 OPEN (value is the number 1). Indicates that the connection has been successful and is ready to communicate. The connection here is persistent connection, persistent connection.

 CLOSING (value is the number 2). Indicates that the connection is ready to be disconnected and the handshake will be cancelled.

 CLOSED (value is the number 3). Indicates that the connection has been disconnected, either from the server or from the client.

URL

The URL attribute is the same, even if you visit the same origin site (the URL address here must be an absolute address). For example:

Var Socket = new WebSocket ('ws://www.test.com/')

Even if the address that initiates the WebSocket connection is www.test.com, it must target ws://www.test.com as the connection target, otherwise it is wrong.

The following three forms are wrong:

Var Socket = new WebSocket ('/')

Var Socket = new WebSocket ('C:\ www.test.com')

Var Socket = new WebSocket ('http://www.test.com');

The following two forms are permissible and correct:

Var Socket = new WebSocket ('ws://www.test.com/updates')

Var Socket = new WebSocket ('ws://www.test.com/updates:8080')

Event

The specific event description is as follows, where the send () method transmits data based on a successful connection, and its parameters must be in string (string) format.

Event handle event type interpretation

Onopen open connection open

Onmessage message is used to receive information from the server

Onerror error is used for fault-tolerant processing and troubleshooting when various errors occur in the connection.

Onclose close connection closed or disconnected

Send send transfers data based on a successful connection

Note here that the bufferedAmount attribute, as the last pending event polling task that has not yet been sent to the network, must return the number of bytes of UTF-8-based text that is being queued (ready to be sent). (this includes text sent during the execution of the current task, regardless of whether the client can transfer text asynchronously or not. )

If the connection is closed, the value of this property will only increase the number change each time you use the send method (once the connection is closed, the number cannot be initialized to 0).

In the following simple example, the bufferedAmount property is used to ensure that the frequency of updates per 50ms can be maintained (if the network can maintain this rate), and if this rate is too fast, it is possible to use other guaranteed rates:

Var Socket = new WebSocket ('ws://www.test.com:12010/updates')

Socket.onopen = function () {

SetInterval (function () {

If (Socket.bufferedAmount = = 0)

Socket.send (getUpdateData ())

}, 50)

}

At this point, the study on "how to use WebSocket API" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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