select根据值动态改变选中项

<script language="javascript">//根据option的value值修改select的默认选项function selectValues(obj,v){  if(obj!=null && v!=null){for (var i = 0; i < obj.options.length; i++) {  if (obj.options(i).value==v) {obj.selectedIndex=i; break;  }}  }}function fun1(){var val = document.getElementById("Tyear").value;var obj = document.getElementById("year");selectValues(obj,val);}</script>

<input  type="text" value="2020" id="Tyear"/><input type="button" onclick="fun1()" value="确定"/><br /><select id="year" name="year" >     <option value="2013" >2013</option>     <option value="2014" selected="selected">2014</option>     <option value="2015" >2015</option>     <option value="2016" >2016</option>     <option value="2017" >2017</option>     <option value="2018" >2018</option>     <option value="2019" >2019</option>     <option value="2020" >2020</option></select>