Getting and setting SharePoint form field values

fd.field('Title').value();

fd.field('Title').value('Default title');

fd.field('Title').change(function(){});

fd.field('MultipleLinePlain').value();

fd.field('MultipleLinePlain')
  .value('MultipleLinePlain');

fd.field('MultilinePlain').change(
  function(){alert('Field has been changed!')}
);

fd.field('MultilineRichText').value();

fd.field('MultilineRichText')
  .value('MultilineRichText');

fd.field('MultilineRichText').change(
  function(){alert('Field has been changed!')}
);

fd.field('MultilineEnhanced').value();

fd.field('MultilineEnhanced')
  .value('MultilineEnhanced');

fd.field('MultilineEnhanced').change(
  function(){alert('Field has been changed!')}
);

fd.field('ChoiceSingle').value();

fd.field('ChoiceSingle').value('B');

fd.field('Choice').change(function(){
  alert('Field changed!');
});

var checkboxIndex = 2;
fd.field('MultiChoice').control()._el()
  .find('input[type="checkbox"]').eq(checkboxIndex)
  .is(':checked');

var checkboxIndex = 2;
fd.field('MultiChoice').control()._el()
  .find('input[type="checkbox"]').eq(checkboxIndex)
  .prop('checked', true);

fd.field('MultiChoice').change(function(){
  alert('Field changed!');
});

fd.field('Number').value();

fd.field('Number').value('13');

fd.field('Number').change(function(){
  alert('Field changed!');
});

fd.field('Currency').value();

fd.field('Currency').value('23');

fd.field('Currency').change(function(){
  alert('Field changed!');
});

fd.field('Date').value();

field('Date').control('getDate') // returns Date-object

fd.field('Date').value('4/21/2012'); // by String

fd.field('DateTime')
  .value(new Date()); // by Date-object

fd.field('Date').change(function(){
  alert('Field changed!');
});

fd.field('DateTime').value()[0]; // date
fd.field('DateTime').value()[1]; // hours
fd.field('DateTime').value()[2]; // minutes

field('DateTime').control('getDate') // returns Date-object

fd.field('DateTime')
  .value(['4/21/2012', '11 PM', '35']); // by Array
fd.field('DateTime')
  .value(new Date()); // by Date-object

fd.field('DateTime').change(function(){
  alert('Field changed!');
});

fd.field('Hyperlink').value()[0]; // link
fd.field('Hyperlink').value()[1]; // descr

fd.field('Hyperlink')
  .value(['http://someurl', 'description']);

fd.field('Hyperlink').change(function() {
  alert('Changed!');
});

fd.field('Lookup').control('getSelectedText');

fd.field('Lookup').value();

fd.field('Lookup').value('Text');

var ID = 4;
fd.field('Lookup').value(ID);

fd.field('Lookup')
  .change(function(){});

var selectedItems = fd.field('LookupMultiple')
  .control()._el().find("select:eq(1) option");
var s = '';
for (var i = 0; i < selectedItems.length; i++) {
  s += selectedItems.eq(i).text() + ';';
}
alert(s);

fd.field('MultiLookup').control()._el()
  .find("select:eq(1) option").eq(0).text()

fd.field('MultiLookup').control()._el()
  .find("select:eq(1) option").eq(1).text()

// first selected:
fd.field('MultiLookup').control()._el()
  .find('select:eq(1) option').eq(0).val(); 

// second selected:
fd.field('MultiLookup').control()._el()
  .find('select:eq(1) option').eq(1).val();

var ID = 3;
// select element by ID:
fd.field('MultiLookup').control()._el()
  .find('select:eq(0)').val(ID); 

// add button click:
fd.field('MultiLookup').control()._el()
  .find('button:eq(0)').click();

fd.field('MultiLookup').change(function(){
  alert('Field changed!');
});

fd.field('Boolean').value();

fd.field('Boolean').value('1');

fd.field('Boolean').change(function(){
  alert('Field changed!');
});

fd.field('User').control('ready', function() {
  var selectedUsers = fd.field('User').value();
  for (var i = 0; i < selectedUsers.length; i++) {
    alert('Login: ' + selectedUsers[i].Key);
  }
});

// assign value by a display name
fd.field('User').value('Tim Watts');

// by a login
fd.field('User').value('DEV\\ann');

// or by an e-mail:
fd.field('User').value('AGibson@contoso.com');

fd.field('User').change(function(){
  alert('Field changed!');
});

var logins = '';
$.each(fd.field('People').value()
  .dictionaryEntries,
  function() {
    logins += this.AccountName + '; ';
  });

fd.field('People').value('DOMAIN\\login');

fd.field('People').change(function(){
  alert('Field changed!');
});

fd.field('PersonGroupSingle')
  .value().dictionaryEntries[0].AccountName

fd.field('Person').value('DOMAIN\\login');

fd.field('Person').change(function(){
  alert('Field changed!');
});

fd.field('ExternalData').value()
  .dictionaryEntries[0]['FieldOfExternalList']

‘ExternalData’ is an internal name of the lookup column.
‘FieldNameOfExternalList’ is an internal name of the external list column.

If you include additional columns to the target list in lookup settings you will be able to get them dynamically as well:

fd.field('ExternalData').value()
  .dictionaryEntries[0]['AdditionalFieldOfExternalList']

‘AdditionalFieldOfExternalList’ is an internal name of the external list column which has been added as additional field in lookup settings.

fd.field('ExternalData')
  .value({key: '__bg40003300', text: 'Item 1'});

key is BDC Identity of the selected item.
text is a display name of the selected item.

fd.field('ExternalData').change(function(){
  alert('Field changed!');
});

fd.field('CrossSiteLookup').value()

fd.field('CrossSiteLookup').control('data')['Title']

fd.field('CrossSiteLookup').value(1);

Set ID and display text:

fd.field('CrossSiteLookup')
  .value({Id: 1, Title: 'Item 1'});

fd.field('CrossSiteLookup').change(function(){
  alert('Field changed!');
});

fd.field('CrossSiteLookup').value()

fd.field('CrossSiteLookup').control('data')[0]['Title']

Second item:

fd.field('CrossSiteLookup').control('data')[1]['Title']

fd.field('CrossSiteLookup')
  .value([{Id: 1, Title: 'Item 1'}, 
    {Id: 2, Title: 'Item 2'}])

fd.field('CrossSiteLookup').change(function(){
  alert('Field changed!');
});