Google Sheets Apps Script

Code.gs

//  1. Run > setup
//    - to set the document id 
//
//  2. Publish > Deploy as web app 
//    - enter Project Version name and click 'Save New Version' 
//    - set security level and enable service (most likely execute as 'me' and access 'anyone, even anonymously) 
//
//  3. Copy the 'Current web app URL' and post this in your form/script action 
//
//  4. Insert column names on your destination sheet matching the parameter names of the data you are passing in (exactly matching case)
//
//  Post data is sent to the web app URL (with support for `?sheetName=CustomSheetName`) with the following JSON schema
//  {
//    "header_row": "Optional, to indicate which row no is the header row",
//    "columnHeader1": "Value 1",
//    "columnHeader2": "Value 2",
//  }

var SCRIPT_PROP = PropertiesService.getScriptProperties(); // new property service

function doPost(e){
  return handleResponse(e);
}
 
function handleResponse(e) {
  // shortly after my original solution Google announced the LockService[1]
  // this prevents concurrent access overwritting data
  // [1] http://googleappsdeveloper.blogspot.co.uk/2011/10/concurrency-and-google-apps-script.html
  // we want a public lock, one that locks for all invocations
  var lock = LockService.getPublicLock();
  lock.waitLock(30000);  // wait 30 seconds before conceding defeat.
   
  var jsonString = e.postData.getDataAsString();
  var jsonData = JSON.parse(jsonString);
  var data = [].concat(jsonData);
  var sheetName = e.parameter.sheetName || 'Sheet1';
  
  try {
    // next set where we write the data - you could write to multiple/alternate destinations
    var doc = SpreadsheetApp.openById(SCRIPT_PROP.getProperty("key"));
    var sheet = doc.getSheetByName(sheetName);
     
    // we'll assume header is in row 1
    var headRow = 1;
    var headers = sheet.getRange(1, 1, 1, sheet.getLastColumn()).getValues()[0];
    var timestamp = new Date();
    
    data.forEach(function(rowData) {
      var nextRow = sheet.getLastRow()+1; // get next row
      var row = []; 
      // loop through the header columns
      for (i in headers){
        if (headers[i] == "Timestamp"){ // special case if you include a 'Timestamp' column
          row.push(timestamp);
        } else { // else use header name to get data
          row.push(rowData[headers[i]]);
        }
      }
      // more efficient to set values as [][] array than individually
      sheet.getRange(nextRow, 1, 1, row.length).setValues([row]);
    });
    // return json success results
    return ContentService
          .createTextOutput(JSON.stringify({"result":"success" }))
          .setMimeType(ContentService.MimeType.JSON);
  } catch(e){
    // if error return this
    return ContentService
    .createTextOutput(JSON.stringify({"result":"error", "error": e }))
          .setMimeType(ContentService.MimeType.JSON);
  } finally { //release lock
    lock.releaseLock();
  }
}
 
function setup() {
    var doc = SpreadsheetApp.getActiveSpreadsheet();
    SCRIPT_PROP.setProperty("key", doc.getId());
}