I have the following scenario:

async function asyncfunc1()
{
      var request = new XMLHttpRequest();
      request.open('GET', requestURL, false);
      request.responseType = 'json';
      request.send();
      return request.response;
}

var res_1 = asyncfunc1(); /* i dont to wait here, just let it work in the background */
res_2 = do some stuff....
res_3 = do more stuff
total_res= res_1 + res_2 + res_3; /* how to wait for res_1 here */