BuildToDesktop.cs

using UnityEditor;
using UnityEngine;

public class BuildToDesktop
{
    [MenuItem("File/Build to Desktop")]
    public static void BuildGame()
    {
        string dateTime = System.DateTime.Now.ToString("yyyy-MM-dd-HH-mm-ss");
        string path = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Desktop) + "/Build_" + dateTime;

        if (!System.IO.Directory.Exists(path))
        {
            System.IO.Directory.CreateDirectory(path);
            BuildPipeline.BuildPlayer(EditorBuildSettings.scenes, path, BuildTarget.WebGL, BuildOptions.None);
        }
        else
        {
            Debug.LogError("Folder already exists, something went wrong!..");
        }
    }
}