Skipping blanks in a Javascript array

Beginner coder here. I could use some assistance.

I have a loop array function that I'm using to automatically fill in values.

Some of these values are intentionally blank. However, it seems the array assigns an "undefined" label to all values that are blank in the array.

Here is the code in question.

 function SubGroup_Update() {


  var Metrics = SpreadsheetApp.openById("10Wl1B4AtdLHJXBbLbMQbSdtRyAb61biCWYpOQEEywIY"); // METRICS spreadsheet
  var Data = SpreadsheetApp.getActiveSpreadsheet(); // DATA spreadsheet

  var SubsMetricSheet = Metrics.getSheetByName('Sub Group Metrics'); // METRICS "Sub Group" sheet 

  var SubGroupDataSheet = Data.getSheetByName("The Sub Group_Numbers") // DATA "Sub Group" sheet
  var SubGroupAllValues = SubGroupDataSheet.getRange(2, 1, SubGroupDataSheet.getLastRow()-1,SubGroupDataSheet.getLastColumn()).getValues();
  var SubsDataLastRow = SubGroupDataSheet.getLastRow(); // Get the number for the amount of rows with info in the DATA "Sub Group" Sheet

  var FeedDataSheet = Data.getSheetByName("The Feed_Raw") // DATA "Feed" sheet
  var FeedAllValues = FeedDataSheet.getRange(2, 1, FeedDataSheet.getLastRow()-1,FeedDataSheet.getLastColumn()).getValues();

  //var SubsDataRange = SubGroupDataSheet.getRange("A2:K");  // The entire range of cells in the DATA "Sub Group" Sheet, for sorting


  var SubGroupObj = {}; // Object for "Subgroup" values


  for(var SG = SubGroupAllValues.length-1;SG>=0;SG--) // for each row in the "Sub Group" sheet...

  {
    //... Add "Sub Group KEY (Col. #11 [K])"& "FYI Category Name (Col. #1 [A])" in Feed 2D Array.
    SubGroupObj[SubGroupAllValues[SG][10]] = SubGroupAllValues[SG][0]; 
  }


  for(var F = FeedAllValues.length-1;F>=0;F--) // for each row in the "Feed" sheet...
  {  
    var Feed_SubGroupKey = FeedAllValues[F][92]; // ...Add "Sub Group (Col. #93 [CO])" in array. 
    {
      // If Sub Group array dont match "Sub Group Key (Col. #93 [CO])"& "FYI Topic Name (Col. #4 [D])... "
      if (SubGroupObj[Feed_SubGroupKey] != FeedAllValues[F][3] ) 
      { 
        FeedAllValues[F][3] = SubGroupObj[Feed_SubGroupKey]; // ...Change FYI Category Name in FYI Topic Sheet 
      }
    }
  }

  // Decalare var. from 2nd row to last row of FYI Topic sheet
  var FeedDestinationRange = FeedDataSheet.getRange(2, 1, FeedAllValues.length, FeedAllValues[0].length); 

  FeedDestinationRange.setValues(FeedAllValues); // placed changed FYI Category 2D array in Mod sheet

  var SubGroupAllRange = SubGroupDataSheet.getRange(2, 1, SubGroupDataSheet.getLastRow()-1,SubGroupDataSheet.getLastColumn()); // complete range of Mod Status sheet 

  // Sort Sheet by - Category Name, then Category Topic
  SubGroupAllRange.sort([{column: 1, ascending: true}, {column: 2, ascending: true}]); 

  Logger.log("The Sub Group Data Sheet has updated  " + SubsDataLastRow-1+ " data files" )

 }

Can anyone help me modify this function so that it will skip over any blank cells it will find in my file? I tried coding it myself, but i had no luck.

I appreciate any assistance.