js 获取select的值 / js动态给select赋值

var t = document.getElementById("select1"); 
		  var selectValue=t.options[t.selectedIndex].value;//获取select的值
		  
		  var t1 = document.getElementById("select2"); 
		  
		  for(i=0;i<t1.length;i++){//给select赋值
			  if(selectValue==t.options[i].value){
				  t1.options[i].selected=true
			  }
		  }
第二种方法，赋值是一样

<script>
	function getSelectValue(){
		var selectCount = document.getElementById("select1").options;
		for(var i = 0 ; i<selectCount.length;i++){
			if(selectCount[i].selected){
				alert(selectCount[i].value);
			}
		}
	}
</script>

<select id="select1" name="select1">
		 <option value="0">0</option>
		 <option value="1">1</option>
		 <option value="2">2</option>
	</select>
	<input type="button" id="button1" value="submit" onclick="getSelectValue()"/>