Array.indexOf(value) - not giving proper index number in GAS

Question

In GAS,

Code.gs
function myFunction() {
  var sheet2 = SpreadsheetApp.getActivesheet();
  var firstset = sheet2.getRange('B1:B10').getValues();
  Logger.log(firstset)
  var found = firstset.indexOf('[re]')
  Logger.log(found)
}

In Google Spreadsheet Range B1:B10,

B1  we
B2  we
B3  re
B4  ef
B5  ge
B6  er
B7  fe
B8  th
B9  rg
B10 pq

The answer to the code should result 2, however, Log is showing -1 (not matched). Any help

Screenshot of Logger.log

Solution

in a simple for loop :

function myFunction() {
  var sheet2 = SpreadsheetApp.getActiveSheet();
  var firstset = sheet2.getRange('B1:B10').getValues();
  for(var n in firstset){
    if(firstset[n][0]=='re'){break}
  }
  Logger.log(n);
}