问 连接到binance api的Websocket返回错误

EN

我想测试到binance wss://testnet-dex.binance.org/api/ws 的websocket连接。但是，每当我运行js脚本时，我都会收到来自 ws 的错误响应。

脚本看起来是这样的

const WebSocket = require('ws');
const conn = new WebSocket("wss://testnet-dex.binance.org/api/ws");
conn.onopen = function(evt) {
    conn.send(JSON.stringify({ method: "subscribe", topic: "trades", symbols: ["ETH_BNB"] })); // I did try using as an symbols 'BNB_USDT.B-B7C', but got the same error
conn.onmessage = function(evt) {
    console.info('received data', evt.data);