<script type="text/javascript">

 //第一步把之前的数据写成一个数组的形式,定义变量为 infos
    var infos= [["小A","女",21,"大一"],["小B","男",23,"大三"],
    ["小C","男",24,"大四"],["小D","女",21,"大一"],
    ["小E","女",22,"大四"],["小F","男",21,"大一"],
    ["小G","女",22,"大二"],["小H","女",20,"大三"],
    ["小I","女",20,"大一"],["小J","男",20,"大三"]]
 
 //第一次筛选，找出都是大一的信息
for(var i=0,i<=9,i++){
    if(infos[i][3]=="大一"){
    document.write(infos[i][0]+"<br/>")
        
    }
} 
  
 //第二次筛选，找出都是女生的信息
 for(var n=0 n<infos.length;n++){
     if(infos[n][3]=="大一"&&infos[n][1]=="女"){
         document.write(infos[i][0]+"<br/>")
     }
 }
 
  
</script>