WebSocket.onopen
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
**WebSocket.onopen**属性定义一个事件处理程序，当WebSocket 的连接状态readyState 变为1时调用;这意味着当前连接已经准备好发送和接受数据。这个事件处理程序通过 事件（建立连接时）触发。
语法
aWebSocket.onopen = function(event) {
console.log("WebSocket is open now.");
};
返回值
An EventListener.
规范
| Specification |
|---|
| WebSockets Standard # dom-websocket-onopen |
浏览器兼容性
BCD tables only load in the browser