Add item to list using button

Question

I try to create button that will be add item to the list. Unfortunately I do somethings wrong. My programming skill's are at beginner level.
I have list "List" with only one field Title (for test) - at default it will be User and Date.

Code that I have use to create item:

function postSurvey()
{
           var context = new SP.ClientContext.get_current();
           var myWeb = context.get_web();
           var myList = myWeb.get_lists().getByTitle('List');
           var itemCreateInfo = new SP.ListItemCreationInformation();
           var listItem = myList.addItem(itemCreateInfo);
           listItem.set_item("Title", Title.value);
           listItem.update();

           context.executeQueryAsync(Function.createDelegate(this, AddNewEmployeeSuccess),Function.createDelegate(this, AddNewEmployeeFail));

function AddNewEmployeeFail(sender, args)
{
  alert('Request failed. ' + args.get_message() + '\n' + args.get_stackTrace());
}
function AddNewEmployeeSuccess(sender, args)
{
  alert('Item created: ' + listItem.get_id());
}
}     

Script:

<script type='text/javascript' src="../SitePages/AddingNewUser.js"></script>

Button def.:

<tr>
  <td><input type='text' id='Title'/></td>  
</tr>
<tr>
  <td><button type="button" id="btnAddCar" onclick="postSurvey()">Add</button></td>
</tr>

After click on Button I don't have AddNewEmployeeFail message - just only "Fail" pop-up.

I try this samples without any results:

http://msdn.microsoft.com/en-us/library/office/hh185011(v=office.14).aspx
http://digsharepoint.blogspot.com/2012/03/javascript-front-end-to-start.html
http://ishaalan.wordpress.com/2010/05/23/adding-an-item-to-a-sharepoint-list-using-javascript/ - with this article I can't find SP.js and I don't know where to put this library.

I'm working on SharePoint Online 2010 (on 2013 will some difference's in code?) .

Answer 1

Setting Title value

The line:

listItem.set_item("Title", Title.name);

is used for setting Title column from Title.name object.

Are you using something like this to initialize Title object?

var Title = {};
Title.name = $('#title').val();

Ensure sp.js library is loaded

In order to ensure that sp.js is loaded, change function your function to

function postSurvey()
{
   SP.SOD.executeOrDelayUntilScriptLoaded(function(){
      var context = new SP.ClientContext.get_current();
      //your remaining code goes here...  
   }, 'sp.js');
}

Answer 2

Try this:

listItem.update();

context.load(listItem);

           context.executeQueryAsync(Function.createDelegate(this, AddNewEmployeeSuccess),Function.createDelegate(this, AddNewEmployeeFail));