让input的值根据select改变

 <select onchange="detail()" id="iden1"  >
            <option value="1">你好</option>
                 <option value="2">我好</option>
        <option value="3">大家好</option>
   </select>

        <input type="text" name="iden" id="iden" value="" />

<script>
    function detail(sel) {
        document.getElementById('iden').value = sel.options[sel.selectedIndex].text;
    }
</script>

 

 

显示对应的数值

<script>
    function detail(sel) {
        document.getElementById('iden').value = sel.options[sel.selectedIndex].value;
    }
</script>