Google Apps Script API Executable Example

function insertTransaction(dateString, description, amount) {
  var result = {
    success: false,
    message: null
  };
  
  try {
    var budgetSpreadsheetId = '<INSERT-SPREADSHEET-ID-HERE>';
    
    // Open the spreadsheet
    var spreadsheet = SpreadsheetApp.openById(budgetSpreadsheetId);
    
    // Determine which sheet to open based on the month of the transaction
    var sheetName = getSheetName(dateString);
    var sheet = spreadsheet.getSheetByName(sheetName);
    
    // Append the new transaction to the table
    sheet.appendRow([dateString, description, amount]);
    
    result.success = true;
    result.message = "Transaction added.";
  }
  catch (e) {
    result.success = false;
    result.message = e.message;
  }
  finally {
    return JSON.stringify(result);
  }
}

function getSheetName(dateString) {
  var sheetNames = [
    "January Transactions",
    "February Transactions",
    "March Transactions",
    "April Transactions",
    "May Transactions",
    "June Transactions",
    "July Transactions",
    "August Transactions",
    "September Transactions",
    "October Transactions",
    "November Transactions",
    "December Transactions",
  ];
    
  // Get the month number, then subtract one to get the 0-indexed value from the sheetNames array
  var monthNumber = parseInt(dateString.substring(5, 7));
  return sheetNames[monthNumber - 1];
}