如何获取select下拉框的值(option没有及有value属性)

如何获取select下拉框的值：
1.下拉框的option没有value属性时

<select id="param1"> 
<option>学号</option> 
<option>姓名</option> 
<option>年龄</option> 
</seclect> 
<script> 
window.onload = funciton(){ 
var param = document.getElementById("param1"); 
param.onchange = getParam(){ 
var text = param.value; 
} 
} 
</script>

2.下拉框的option有value属性时

<select id="param1"> 
<option>学号</option> 
<option>姓名</option> 
<option>年龄</option> 
</seclect> 
<script> 
window.onload = funciton(){ 
var param = document.getElementById("param1"); 
param.onchange = getParam(){ 
var selectIndex = param.selectIndex; //获得被选项的引索号 
var text = param.options[selectIndex].text; 
</script>