Convert XMLHttpRequest into Web Socket

Question

I have a function that opens a connection to a server and logs the response. The function is using XMLHttpRequest, I want the very same function using Web Socket instead. Is this possible? Here is my code:

function httpGetAsync(theUrl, callback){
    let token = "ABC123";

    var xmlHttp = new XMLHttpRequest();
    xmlHttp.onreadystatechange = function() { 
        if (xmlHttp.readyState == 4 && xmlHttp.status == 200)
            callback(xmlHttp.responseText);
        }
    xmlHttp.open("GET", theUrl, true);
    xmlHttp.setRequestHeader('Authorization', 'Bearer ' + token);
    xmlHttp.send(null);
}

What I have tried so far:

function wsTest(url){
    if ("WebSocket" in window) {
        var ws = new WebSocket(url);

        ws.onopen = function() {
          ws.send('Authorization', 'Bearer ' + token);
        };

        ws.onmessage = function (evt) { 
          var received_msg = evt.data;
          console.log("Message is received...");
          console.log(received_msg);
        };

        ws.onclose = function() { 
          console.log("Connection is closed..."); 
        };
    }
}

I can't figure out how to properly add the xmlHttp.setRequestHeader('Authorization', 'Bearer ' + token); part to the Web Socket.