//间隔发送心跳包数据给服务器，服务器在一定时间内发回心跳包响应，对比超时限定，如果超过设定的超时时间，则认为当前与服务器的websocket连接已经断开，关闭当前web socket连接，善后处理，例如重新连接，或者弹出提示……
function keepalive(ws) {
var time = new Date();
if (last_health != -1 && (time.getTime() – last_health > health_timeout)) {
//连接断开，可设置重连或者关闭连接
(“#keeplive_box”).html(“服务器没有响应.”).css({
“color” : “red”
});
//ws.close();
} else {(“#keeplive_box”).html(“连接正常”).css({
“color” : “green”
});
if (ws.bufferedAmount == 0) {
ws.send(‘~H#C~’);
}
}
}
var ws = new WebSocket(to_url);
ws.onopen = function () {
(“#statustxt”).html(“connected.”);(“#send_btn”).attr(“disabled”, false);
heartbeat_timer = setInterval(function () {
keepalive(ws)
}, 3000);
}
