//**1.设置选中值:(根据索引确定选中值)**// var osel=document.getElementById("selID"); //得到select的ID var opts=osel.getElementsByTagName("option");//得到数组option var obt=document.getElementById("bt"); obt.onclick=function(){ opts[3].selected=tr
js函数方法: <script> function getDefaultSelectedOption(selectId, valIfNull) { var selectId = selectId.replace(/^#/, ''), opts; try { opts = document.getElementById(selectId).getElementsByTagName('option'); for (var i in opts) { if (opts[i].defaultSelect