方法1：原生JavaScript
设置CSS
table td{
border:red solid 1px;
}
.tr1{
color:white;
background: black;
}
.tr2{
color:black;
background: white;
}
.tr2:hover{
color:red;
background: yellow;
}
设置JavaScript
（1）获取tr标签
var ctr=document.getElementById("tab").getElementsByTagName("tr");
（2）使用循环
function fun(){
for(i=0;i<ctr.length;i++){
ctr[i].className=((i+1)%2>0)?"tr1":"tr2";
}
}
（3）调用js
window.onload=fun;
注意事项：该JavaScript代码需要在加载完毕后执行。
点击查看完整代码
<!doctype html> <html> <head> <meta charset="utf-8"> <title>index</title> <style> table td{ border:red solid 1px; } .tr1{ color:white; background: black; } .tr2{ color:black; background: white; } .tr2:hover{ color:red; background: yellow; } </style> </head> <body> <table id="tab"> <tr> <td>mllt</td> <td>mllt</td> <td>mllt</td> </tr> <tr> <td>mllt</td> <td>mllt</td> <td>mllt</td> </tr> <tr> <td>mllt</td> <td>mllt</td> <td>mllt</td> </tr> <tr> <td>mllt</td> <td>mllt</td> <td>mllt</td> </tr> <tr> <td>mllt</td> <td>mllt</td> <td>mllt</td> </tr> <tr> <td>mllt</td> <td>mllt</td> <td>mllt</td> </tr> <tr> <td>mllt</td> <td>mllt</td> <td>mllt</td> </tr> <tr> <td>mllt</td> <td>mllt</td> <td>mllt</td> </tr> <tr> <td>mllt</td> <td>mllt</td> <td>mllt</td> </tr> <tr> <td>mllt</td> <td>mllt</td> <td>mllt</td> </tr> </table> </body> <script> var ctr=document.getElementById("tab").getElementsByTagName("tr"); function fun(){ for(i=0;i<ctr.length;i++){ ctr[i].className=((i+1)%2>0)?"tr1":"tr2"; } } window.onload=fun; </script> </html>