Conditional borders in Google Sheets

I am trying to do exactly what Add border format to row if condition met in Google Sheets is asking, but the accepted answer simply does not work. The original post was very clear, so here it is once more:

Excel apparently has this type of conditional formatting built-in.

I'd like to accomplish the same in Google Sheets via Google Apps Script. The following should demonstrate the before and after conditions:

Example Dataset

        A           B           C
  1   apple     Macintosh
  2   apple     Granny Smith
  3   orange    Florida
  4   orange    Valencia
  5   pear      Garden
  6   banana    Chiquita

Resulting Example Dataset

        A           B           C
  1   apple     Macintosh
  2   apple     Granny Smith
  -----------------------------------
  3   orange    Florida
  4   orange    Valencia
  -----------------------------------
  5   pear      Garden
  -----------------------------------
  6   banana    Chiquita
  -----------------------------------  

The script/answer to this question should display a bottom border under the entire row (of columns 'A', 'B' & 'C') for rows: 2, 4, 5, & 6.

The accepted answer to this original post provides the following script:

function onOpen() {
   GroupMyData(); // trigger this function on sheet opening
}

function GroupMyData() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getSheetByName('Sheet 1'); // apply to sheet name only
  var rows = sheet.getRange('a1:g'); // range to apply formatting to
  var numRows = rows.getNumRows(); // no. of rows in the range named above
  var values = rows.getValues(); // array of values in the range named above
  var testvalues = sheet.getRange('a1:a').getValues(); // array of values to be tested (1st column of the range named above)

  rows.setBorder(false, false, false, false, false, false, "red", SpreadsheetApp.BorderStyle.SOLID_MEDIUM); // remove existing borders before applying rule below
      //Logger.log(numRows);

  for (var i = 0; i <= numRows - 1; i++) {
      var n = i + 1;
      //Logger.log(n);
      //Logger.log(testvalues[i] > 0);
      //Logger.log(testvalues[i]);
      if (testvalues[i] > 0) { // test applied to array of values
        sheet.getRange('a' + n + ':g' + n).setBorder(null, null, true, null, null, null, "red", SpreadsheetApp.BorderStyle.SOLID_MEDIUM); // format if true
      }
  }
};

That script functions like so: A border will appear along the bottom of each row where column A's cell has a number in it (and no letters), regardless of whether the number is the same as the one in the cell above it or different.

However the goal is for A to have text, and wherever consecutive text down column A changes from a repeated string to a differing string, there should be a border between the differing strings.

The Questioner refers to a previous Q&A which was based on evaluating a number. In the questioners case, the evaluation is based on a string.

I referred to the question noted by the Questionner. I also referred to How to compare strings in google apps script which contains a very elegant and efficient approach by Harold which I have carried through in this answer. This uses indexof to detect new values, and so underlining can be linked with each new value.

function so53053492() {

    //setup spreadsheet
    var ss = SpreadsheetApp.getActiveSpreadsheet();
    var sheet = ss.getSheetByName("Sheet1");

    // get key variables
    var LastRow = sheet.getLastRow();
    var LastColumn = sheet.getLastColumn();

    //erase any current formatting 
    var ClearRange = sheet.getRange(1, 1, LastRow, LastColumn).setBorder(false, false, false, false, false, false); // clear all formatting

    // get the data
    var data = sheet.getRange(1, 1, sheet.getLastRow(), sheet.getLastColumn()).getValues();

    // setup new array  
    var ListofFruits = new Array();

    // Loop through the fruits (Column A)
    for (var i in data) {
        var row = data[i][0].toString();


        // search for unqiue values
        if (ListofFruits.indexOf(row) == -1) { // if value =-1, then the variable is unique

            // Logger.log(row+" is not referenced. Adding it");//DEBUG
            // underline the previous row
            var range = sheet.getRange((+i + 1), 1, 1, 2).setBorder(true, false, false, false, false, false, "red", SpreadsheetApp.BorderStyle.SOLID_MEDIUM); // format if true

            // continue to build array
            ListofFruits.push(row);
        }

    }
    // underline the last row of the fruits column
    var range = sheet.getRange(LastRow, 1, 1, LastColumn).setBorder(null, null, true, null, false, false, "red", SpreadsheetApp.BorderStyle.SOLID_MEDIUM); // format if true
    // Logger.log(ListofFruits);// DEBUG
}

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UPDATE - Accounting for Headers

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The previous version assumed no headers. This version takes headers into account. There are several lines of code affected, but the key variable is headerRows which allows the user to nominate the depth of the headers.

function so53053492_01() {

    //setup spreadsheet
    var ss = SpreadsheetApp.getActiveSpreadsheet();
    var sheet = ss.getSheetByName("Sheet3");

    // get key variables
    var LastRow = sheet.getLastRow();
    var LastColumn = sheet.getLastColumn();
    var NumColumns = sheet.getMaxColumns();

    // allow for headers
    var headerRows = 2;

    //erase any current formatting 
    var ClearRange = sheet.getRange(1, 1, LastRow, NumColumns).setBorder(false, false, false, false, false, false); // clear all formatting

    // get the data
    var data = sheet.getRange((+1 + headerRows), 1, (LastRow - headerRows), LastColumn).getValues();

    // setup new array  
    var ListofFruits = new Array();

    // Loop through the fruits (Column A)
    for (var i in data) {

        var row = data[i][0].toString();
        // Logger.log("Inside LOOP: i = "+i+", value = "+ row);// DEBUG

        // search for unqiue values
        if (ListofFruits.indexOf(row) == -1) { // if value =-1, then the variable is unique

            // Logger.log("Inside IF#1: i = "+i+", "+row+" is not referenced. Adding it");//DEBUG
            // underline the previous row

            if (i != 0) {
                // This IF statement to avoid underlining the Header row
                var range = sheet.getRange((+i + 1 + headerRows), 1, 1, NumColumns).setBorder(true, false, false, false, false, false, "red", SpreadsheetApp.BorderStyle.SOLID_MEDIUM); // format if true
            }
            // continue to build array
            ListofFruits.push(row);
        }

    }
    // underline the last row of the fruits column
    var range = sheet.getRange(LastRow, 1, 1, NumColumns).setBorder(null, null, true, null, false, false, "red", SpreadsheetApp.BorderStyle.SOLID_MEDIUM); // format if true
    //Logger.log(ListofFruits);// DEBUG
}

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Screenshot showing headers:

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