问答详情
源自：4-10 编程练习

循环筛选和二次筛选

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"]];

var j=0；

 var arr=new Array();

 for(i=0;i<infos.length;i++)

 {

  if(infos[i][3]=="大一")

  {

      document.write(infos[i]+"<br>");

      arr[j]=infos[i];

    j++;

  }

  }

document.write("第二次筛选"+"<br>")

for(i=0;i<arr.length;i++)

  {

      if(arr[i][1]=="女")

      {

          document.write(arr[i][0]+"<br>")

      }

  }

上面j++去掉之后 为什么只能存储最后一次的值 

arr[j++]=infos[i]和arr[j]=infos[i];j++一样吗？

如果一样的话 arr[0]里面有数值吗？

提问者：艾零 2017-07-01 11:20

个回答

  • qq_知秋落葉_0
    2017-12-21 11:05:44

    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"]];
for (i = 0;i<=infos.length;i++){
    if(infos[i][3] == "大一" && infos[i][1] == "女"){
        document.write(infos[i][0]+"<br/>");
    }
}


    0
  • 艾零
    2017-07-01 11:28:29

    j++先取j的值 再加1   ++j先取j的值加1 

    0