Add values and retrieve as JSON from a Google Sheet

SheetURL.gs

function doGet(e) {
  var lock = LockService.getPublicLock();
  lock.waitLock(30000);

  var file = SpreadsheetApp.openByUrl(e.parameter.sheetUrl);
  //Select the first page in the Sheet document  
  var sheet = file.getSheets()[0];
//   if(e.parameter.sheetName) {
//      sheet = file.getSheetByName(unescape(e.parameter.sheetName));
//   }
  
  switch(e.parameter.action) {
//     case "pages":
//       return get_pages(file);
    case "insert":
       var title = unescape(e.parameter.title);
       var url = unescape(e.parameter.url)
       return insert_value(title, url, sheet);
    case "read":
      return get_values(sheet);
    default:
       return ContentService
            .createTextOutput(JSON.stringify({"error":"unexpected action parameter"}))
            .setMimeType(ContentService.MimeType.JSON);
  }
}

//Get Sheet document pages
//function get_pages(file) {
//  var sheets = file.getSheets();
//  
//  var jsonArray = [];
//  for(var i=0; i<sheets.length; i++) {
//    var sheet = sheets[i].getName(); 
//    var entry = {
//      "page": sheet
//    };
//    jsonArray.push(entry);
//  }
//  
//  return ContentService.createTextOutput(JSON.stringify(jsonArray)).setMimeType(ContentService.MimeType.JSON);  
//}
 
function insert_value(title, url, sheet) {
  try {  
      var rowData = sheet.appendRow([title, url]);
      return ContentService
          .createTextOutput(JSON.stringify({"result":"success"}))
          .setMimeType(ContentService.MimeType.JSON);
  } catch(e){
      return ContentService
          .createTextOutput(JSON.stringify({"result":"error"}))
          .setMimeType(ContentService.MimeType.JSON);
  }
}

function get_values(sheet) {
  
  var lastRow = sheet.getLastRow();
  var rowValues = [];
  for(var rowIndex=1; rowIndex<=lastRow; rowIndex++) {
    var colStartIndex = 1;
    var rowNum = 1;
    var range = sheet.getRange(rowIndex, colStartIndex, rowNum, sheet.getLastColumn());
    var values = range.getValues();
    rowValues.push(values[0]);
  }

  // create json
  var jsonArray = [];
  var numberOfRows = rowValues.length
  for(var i=0; i<numberOfRows; i++) {
    var line = rowValues[i];
    var title = line[0];
    var url = line[1];
    
    var entry = {
      "title": title,
      "url": url
    };
    jsonArray.push(entry);
  }
  
  return ContentService.createTextOutput(JSON.stringify(jsonArray)).setMimeType(ContentService.MimeType.JSON); 
}