用js实现websocket

1. 创建WebSocket对象:

```javascript
var socket = new WebSocket('ws://localhost:8080');
```

2. 监听WebSocket事件：

```javascript
socket.onopen = function() {
console.log('WebSocket连接已经打开');
};

socket.onmessage = function(event) {
console.log('接收到消息: ' + event.data);
};

socket.onclose = function() {
console.log('WebSocket连接已经关闭');
};
```

3. 发送WebSocket消息：

```javascript
socket.send('Hello, WebSocket!');
```

完整例子：

```javascript
var socket = new WebSocket('ws://localhost:8080');

socket.onopen = function() {
console.log('WebSocket连接已经打开');
};

socket.onmessage = function(event) {
console.log('接收到消息: ' + event.data);
};

socket.onclose = function() {
console.log('WebSocket连接已经关闭');
};

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

socket.send('Hello, WebSocket!');