js给下拉列表赋值

js给下拉列表赋值

<select  id="Test">
 <option value="">请选择</option>
 <option value="1">1</option>
 <option value="2">2</option>
 <option value="3">3</option>
</select>
<input type="button" value="Btuchange" onclick="onclick();">

function onclick() {
 document.getElementById("Test").value="2";
 
}