Google App Script for logging temperature values in Google Sheet file

code.gs

// From https://github.com/varul29/SHT25_GoogleSheets_GoogleScript?source=post_page-----27912740e74a----------------------

var filename = 'temp_log_sheet';
var sheetName = 'values';
var columns = ['time', 'celsius', 'location'];

function getSheet() {
  var files = DriveApp.getFilesByName(filename);
  var file;
  var didCreateFile = false;
  if(files.hasNext()) {
    file = files.next();
  }
  else {
    file = SpreadsheetApp.create(filename, 1, columns.length);
    didCreateFile = true;
  }
  var spreadsheet = SpreadsheetApp.openById(file.getId());
  var sheet = spreadsheet.getSheets()[0];
  if(didCreateFile) {
    var range = sheet.getRange(1, 1, 1, columns.length);
    range.setValues([columns]);
    sheet.setName(sheetName);
  }
  return sheet;
}

function doGet(request) {
  var output = ContentService.createTextOutput();
  var sheet = getSheet();
  var row = sheet.getLastRow();
  var json;
  if(row == 1) {
    json = JSON.stringify({
      'error' : 'No data available!'
    });
  }
  else {
    var range = sheet.getRange(row, 1, 1, columns.length);
    var values = range.getValues()[0];
    var data = {};
    for(var i = 0; i < columns.length; i++) {
      data[columns[i]] = values[i];
    }
    json = JSON.stringify({ 'data' : data });
  }
  output.append(json);
  output.setMimeType(ContentService.MimeType.JSON);
  return output;
}

function doPost(request) {
  Logger.log(JSON.stringify(request));
  var output = ContentService.createTextOutput();
  var celsius = request.parameter[columns[1]];
  var location = request.parameter[columns[2]];
  var json;
  if(celsius == null || String(Number(celsius)) == 'NaN' || typeof location != 'string') {
    json = JSON.stringify({
      'error' : 'Bad request!'
    });
  }
  else {
    var values = [
      new Date().toISOString(),
      celsius,
      location
    ];
    var sheet = getSheet();
    var row = sheet.getLastRow() + 1;
    var range = sheet.getRange(row, 1, 1, columns.length);
    range.setValues([values]);
    sheet.setFrozenRows(1);
    json = JSON.stringify({
      'success' : 'New record created!'
    });
  }
  output.append(json);
  output.setMimeType(ContentService.MimeType.JSON);
  return output;
}

test.gs

function testGET() {
  var url = ScriptApp.getService().getUrl();
  Logger.log(url);
  var options = {
    'method'  : 'GET',  
    'followRedirects' : true,
    'muteHttpExceptions': true
  };
  Logger.log(JSON.stringify(options));
  var result = UrlFetchApp.fetch(url, options);
  if (result.getResponseCode() == 200) {
    Logger.log(result.getContentText());
  }
  else {
    Logger.log('Error ' + result.getResponseCode());
  }
}

function testPOST() {
  var url = ScriptApp.getService().getUrl();
  Logger.log(url);
  var payload = {
    'celsius' : 0,
    'location' : 'test'
  };
  var options = {
    'method'  : 'POST',
    'payload' : payload,   
    'followRedirects' : true,
    'muteHttpExceptions': true
  };
  Logger.log(JSON.stringify(options));
  var result = UrlFetchApp.fetch(url, options);
  if (result.getResponseCode() == 200) {
    Logger.log(result.getContentText());
  }
  else {
    Logger.log('Error ' + result.getResponseCode());
  }
}