How to Add items in Drop Down List or List Box using Javascript?

<script type="text/javascript">
    function AddItem(Text,Value)
    {
        // Create an Option object
 
       
        var opt = document.createElement("option");
        
        // Add an Option object to Drop Down/List Box
        document.getElementById("DropDownList").options.add(opt);
        // Assign text and value to Option object
        opt.text = Text;
        opt.value = Value;
               
    }
<script />