https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API/Writing_WebSocket_client_applications

socket.js

var URL = "http://localhost:8080/";

var Socket = function(url)
{
    // Global properties
    this.url = url;
    this.connection = new WebSocket(URL);
    
    // Global functions
    this.send = function(msg)
    {
       this.connection.send(msg);
    }
    
    // Private functions
    this.connection.onmessage = function (event)
    {
        console.log(event.data);
    }
}

var socket = new WebSocket(URL);
socket.send("uik");