How can I check JavaScript arrays for empty strings?

You have to check in through loop.

function checkArray(my_arr){
   for(var i=0;i<my_arr.length;i++){
       if(my_arr[i] === "")   
          return false;
   }
   return true;
}

You can check by looping through the array with a simple for, like this:

function NoneEmpty(arr) {
  for(var i=0; i<arr.length; i++) {
    if(arr[i] === "") return false;
  }
  return true;
}

You can give it a try here, the reason we're not using .indexOf() here is lack of support in IE, otherwise it'd be even simpler like this:

function NoneEmpty(arr) {
  return arr.indexOf("") === -1;
}

But alas, IE doesn't support this function on arrays, at least not yet.