Compare arrays, including from other spreadsheets, and count similarities

gistfile1.txt

function bamboo(){
 // var ss = SpreadsheetApp.openByUrl('');
//  var ss = importrange("");
  var ss17 = SpreadsheetApp.getActive();
  var sheet = ss17.getSheets()[1];
  var values = sheet.getRange("A2:A").getValues();
  var lastRow = values.filter(String).length;

  //Current year
   var sheet17 = ss17.getSheets()[0];
   var values17 = sheet17.getRange("Z2:Z").getValues();
   var lastRow17 = values17.filter(String).length;
   var test = new Array();
   var results = new Array();
   var count = 0;
  
  //because .getValues returns an object, need to turn into an array e.g. one column
  for (var n = 0; n < lastRow17; n++){
    test.push(values17[n][0]);
   
   }; Logger.log(test.length);
 
  for (var i = 0; i < values.length; i++) {     
    if(test.indexOf(values[i][0]) >=0){    
      results.push(test.indexOf(values[i][0]));
    };
  };
  Logger.log(results.length);
  return results.length;
};