jquery select set selectindex

To Read Select Option Value

$('#selectId').val(); 

To Set Select Option Value

$('#selectId').val('newValue'); 

To Read Selected Text

$('#selectId>option:selected').text(); 

// sets selected index of a select box to the option with the value "0" 
$("select#elem").val('0');  
 
// sets selected index of a select box to the option with the value "" 
$("select#elem").val('');  
 
// sets selected index to first item using the DOM 
$("select#elem")[0].selectedIndex = 0;