删除/添加 /隐藏/显示-Jquery

1.$(function(){
    $("#data tbody tr:odd").css("background-color","antiquewhite");

    $("#data tbody tr:even").css("background-color","cornflowerblue");

$("#add").click(function(){
var a = "<tr><td>Allen</td><td>$3700</td><td>2011-12-05</td><td><a href='#'>删除</a></td></tr>";
 //<tr><td>Allen</td><td>$3700</td><td>2011-12-05</td><td><a href='#'>删除</a></td></tr>
$("#data tbody").append(a);
$("#data tbody tr:even").css("background-color","cornflowerblue");
$("#data tbody tr:odd").css("background-color","antiquewhite");
$("#data tbody td a").click(removetr);

});

$("#data tbody td a").click(removetr);

function removetr(){

var b =$(this).parent().parent();
b.remove();
$("#data tbody tr:even").css("background-color","cornflowerblue");
$("#data tbody tr:odd").css("background-color","antiquewhite");
  };
    });

    //">"只找到该元素下一个群子元素，空格找到该标签下所有元素；

2.    $(function(){
    $("span").click(function(){

    if($(this).hasClass("open")){
    $(this).attr("class","closed");//attr()一个值获得属性，两个设置
    $(this).next().attr("class","hide");
    }
    else{
    $(this).attr("class","open");
    $(this).next().attr("class","show")
    }
    });

 });