I am trying to use Websocket for the first time but am not able to get the values of property of event object.

Here's my script

let socket = new WebSocket('wss://stream.binance.com:9443/ws/ethusdt@kline_1m')

let o = {
  "method": "SUBSCRIBE",
  "params": [
    "ethusdt@kline_1m"
  ],
  "id": 1
}

socket.send(JSON.stringify(o)) 

socket.addEventListener('message', (e)=>{let candle = e.data; console.log(candle['k'])})

e.data returns object like this :

{
  "e": "kline",     // Event type
  "k": {
    "o": "0.0010",  // Open price
    "c": "0.0020",  // Close price
    "h": "0.0025",  // High price
    "l": "0.0015",  // Low price
  }
}

However, my script always returns undefined.

How can I get those values?