单击时如何自动更改选项标签的选定项目

Question

i want to change the selected item using option tag dynamically. The following values inside in the dropdown button are the links from another page. But the result, when i select a value in the dropdown button, the value of option tag is not changing.

Here is my code:

<select name="select_item" class="select_item" id="menu1" onchange="function();">
                            <option value="<?= base_url('index/products'); ?>">Default sorting</option>
                            <option value="<?= base_url('index/prod_sort1'); ?>">Sort by A to Z</option>

                        </select>
                        <script type="text/javascript">
                            var urlmenu = document.getElementById( 'menu1' );
                            urlmenu.onchange = function() {
                            window.open( this.options[ this.selectedIndex ].value,"_self" );
                            };
                            </script>

Answer 1

Try this code

 <script type="text/javascript">
       var urlmenu = document.getElementById( 'menu1' );
       urlmenu.onchange = function() {
       window.location.href = urlmenu.options[urlmenu.selectedIndex].value;
       }  
 </script>

</div>