getElementById check multiple conditions

I am trying to build a function that checks if all fields are populated, if populated then show div if not hide.

I can get this to work on one fields however i have then tried two ways of checking multiple.

first if first condition met I then ran other condition checking second field nested inside the first... this done not work.

second I passed in an array of ID's rather than a single... this did not work either..

I am left with a working function that only works if first filed is populated can anyone think of a solution to this or maybe i passed in my array incorrectly.

My code

var myVar = setInterval(myTimer, 10);

function myTimer() {

if(!document.getElementById('Email').value) { // I need this to pass if multiple id's
          var divsToHide = document.getElementsByClassName("somediv"); //divsToHide is an array
            for(var i = 0; i < divsToHide.length; i++){
                divsToHide[i].style.visibility = "hidden"; // or
                divsToHide[i].style.display = "none"; // depending on what you're doing

        }
    }
  else {
   var divsToHide = document.getElementsByClassName("somediv"); //divsToHide is an array
            for(var i = 0; i < divsToHide.length; i++){
                divsToHide[i].style.visibility = "visible"; // or
                divsToHide[i].style.display = "block"; // depending on what you're doing
  }
  }
}