WebSocket ReadyState: A Comprehensive Guide

Introduction

WebSocket is an advanced technology that allows bidirectional communication over a single, reliable connection. It is a protocol that allows for real-time communication between a client and a server. WebSocket is gaining popularity among developers because of its low latency, high throughput, and low overhead. One of the critical components of the WebSocket API is the readyState property. In this article, we will discuss WebSocket ReadyState in detail.

What is ReadyState?

The readyState property is a part of the WebSocket API that provides information about the current state of the WebSocket connection. It is an integer value that ranges from 0 to 3, and each value corresponds to a specific state of the connection. The readyState property is read-only, which means that you cannot change its value directly.

The Four States of ReadyState

  1. CONNECTING (0)
  2. The WebSocket connection is being established. This is the initial state of the WebSocket connection. In this state, the WebSocket object has been created, and the connection has been initiated, but the connection is not yet open. This state is also called the “uninitialized” state.

  3. OPEN (1)
  4. The WebSocket connection is open, and communication is possible between the client and the server. In this state, the WebSocket object has successfully connected to the server, and the connection is open. This state is also called the “open” state.

  5. CLOSING (2)
  6. The WebSocket connection is in the process of closing. In this state, the WebSocket object is in the process of closing the connection. This state is also called the “closing” state.

  7. CLOSED (3)
  8. The WebSocket connection is closed or could not be established. In this state, the WebSocket object has either closed the connection or could not establish a connection. This state is also called the “closed” state.

How to Access ReadyState

You can access the readyState property by using the WebSocket object. The readyState property is a read-only property, which means that you cannot change its value directly. You can use the readyState property to determine the current state of the WebSocket connection.

Here is an example:

const socket = new WebSocket('ws://localhost:8080');

console.log(socket.readyState);

This code will output the current readyState of the WebSocket connection. If the connection is not yet established, the readyState will be 0 (CONNECTING). If the connection is open, the readyState will be 1 (OPEN).

WebSocket ReadyState Events

The WebSocket API provides several events that you can use to handle changes in the readyState of the WebSocket connection. These events are fired when the readyState of the WebSocket connection changes.

onopen

The onopen event is fired when the WebSocket connection is open (readyState is 1). You can use this event to send data to the server or to perform any other actions that you need to do when the connection is open.

Here is an example:

const socket = new WebSocket('ws://localhost:8080');

socket.onopen = function() {console.log('WebSocket connection is open');};

This code will log a message to the console when the WebSocket connection is open.

onmessage

The onmessage event is fired when a message is received from the server. You can use this event to handle incoming data from the server.

Here is an example:

const socket = new WebSocket('ws://localhost:8080');

socket.onmessage = function(event) {console.log('Received message: ' + event.data);};

This code will log the message received from the server to the console.

onclose

The onclose event is fired when the WebSocket connection is closed (readyState is 3). You can use this event to handle the closing of the WebSocket connection.

Here is an example:

const socket = new WebSocket('ws://localhost:8080');

socket.onclose = function(event) {console.log('WebSocket connection is closed with code: ' + event.code);};

This code will log the reason for closing the WebSocket connection to the console.

onerror

The onerror event is fired when an error occurs with the WebSocket connection. You can use this event to handle errors that occur during the WebSocket connection.

Here is an example:

const socket = new WebSocket('ws://localhost:8080');

socket.onerror = function(error) {console.error('WebSocket error: ' + error);};

This code will log the error that occurred during the WebSocket connection to the console.

WebSocket ReadyState Best Practices

Here are some best practices that you can follow when using the WebSocket API:

Handle Errors

You should always handle errors that occur during the WebSocket connection. Use the onerror event to handle errors that occur with the WebSocket connection.

Check ReadyState before Sending Data

You should always check the readyState of the WebSocket connection before sending data. You should only send data when the readyState is 1 (OPEN).

Handle Disconnections

You should always handle disconnections that occur during the WebSocket connection. Use the onclose event to handle the closing of the WebSocket connection.

Keep Messages Small

You should keep messages small to reduce the overhead of the WebSocket connection. Large messages can cause performance issues and increase latency.

Use Secure WebSocket Connections

You should use secure WebSocket connections (wss://) to ensure that communication between the client and server is secure. Unsecured WebSocket connections (ws://) can be intercepted by attackers.

FAQs

What is WebSocket?

WebSocket is an advanced technology that allows bidirectional communication over a single, reliable connection. It is a protocol that allows for real-time communication between a client and a server.

What is ReadyState?

The readyState property is a part of the WebSocket API that provides information about the current state of the WebSocket connection. It is an integer value that ranges from 0 to 3, and each value corresponds to a specific state of the connection.

What are the Four States of ReadyState?

The four states of readyState are CONNECTING (0), OPEN (1), CLOSING (2), and CLOSED (3).

How to Access ReadyState?

You can access the readyState property by using the WebSocket object. The readyState property is a read-only property, which means that you cannot change its value directly.

What are WebSocket ReadyState Events?

The WebSocket API provides several events that you can use to handle changes in the readyState of the WebSocket connection. These events are fired when the readyState of the WebSocket connection changes.

What are the Best Practices for Using the WebSocket API?

The best practices for using the WebSocket API are handling errors, checking the readyState before sending data, handling disconnections, keeping messages small, and using secure WebSocket connections.