coloring sunday and saturday on datetime columns on google spreadsheet

colorRows.js

/**
 */
function colorRows() {
  var sheet = SpreadsheetApp.getActiveSheet();
  var rows = sheet.getDataRange();
  var numRows = rows.getNumRows();
  var range = sheet.getRange(2, 1, sheet.getLastRow()); 
  var check = range.getValues();
  
  for (var i = 1; i < numRows - 2; i++) {
    var weekday = (((new Date(check[i][0]).getDay()) + 6) % 7) + 1;
    Logger.log(weekday);
    if (weekday == 6) {
      sheet.getRange(i + 1, 1).setBackground("#ccccff");
    } else if (weekday == 7) {
      sheet.getRange(i + 1, 1).setBackground("#ffcccc");
    }
  }
};