错误信息：WebSocket connection to 'ws://127.0.0.1:8888/' failed: Error during WebSocket handshake: net::ERR_INVALID_HTTP_RESPONSE
请教下这是啥情况咋解决

service代码

$socket=socket_create(AF_INET,SOCK_STREAM,SOL_TCP);
    echo 'server start';
    if(socket_bind($socket,"127.0.0.1",8888)==false){
        echo 'server bind fail:'.socket_strerror(socket_last_error());
    }
    if(socket_listen($socket,0) == false){
        echo 'server listen fail:'.socket_strerror(socket_last_error());
    }
    while (true){
        $accept=socket_accept($socket);
        if($accept!=false){
            $string=socket_read($accept,1024);
            echo 'server receive is :'.$string.PHP_EOL;//PHP_EOL为php的换行预定义常量
            if($string!=false){
                $return_string='server receive is :'.$string.PHP_EOL;
                $ret = socket_write($accept,$return_string,strlen($return_string));
                var_dump($ret);
            }else{
                echo 'socket_read is fail';
            }
            socket_close($accept);
        }
    }
    socket_close($socket);

client

<script>
    var ws = new WebSocket("ws://127.0.0.1:8888");
    ws.onopen = function (event) {
        console.log("open");
        ws.send("hello");
    };
    ws.onmessage = function (p1) {
        console.log(p1)
    };
    ws.onerror = function(evt)
    {
        console.log("WebSocketError!");
        console.log(evt);
    };
</script>