Changing the selected value of a drop-down list using jQuery?

[jQuery.val] checks or selects all the Radio buttons,Checkboxes,and Select options(Dropdown lists) that match the set of values.
For Example:-
Suppose,we have a Dropdownlist called ddl_employees whose value we have to change,
Then we will write as:-

$(".ddl_employees").val('4');

Now,ddl_employee dropdownlist value will be changed to 4.