js弹出模式对话框，并接收回传的值

弹出对话框的页面A：

<script type="text/javascript">
    function openDialog(){
        paramers="dialogWidth:500px; dialogHeight:300px; status:no";
        workerId = window.showModalDialog("userList.aspx","",paramers);
        if(workerId!=undefined && workerId!=""){
            document.getElementById("leader").value = workerId;
          }
        }
</script>

模式对话框js：

 <input type="button" value="选择" onclick="javascript:selectPositionAndClose();"/>
        
    </form>
<script type="text/javascript">
	function selectPositionAndClose(){
		var obj = document.getElementById("userList");
		
		var user = "";
		for(var i=0;i<obj.options.length;i++){
		    
			if(obj.options[i].selected==true){
				user = obj.options[i].value;
			}
		}
		
		window.returnValue = user;
		window.close();
	}
</script>