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;