难得听课（小声bb）
<!doctype html> <html> <head> <meta charset="utf-8"> <title>随机更改背景颜色</title> <script type="text/javascript"> var table,color; function $(id){return document.getElementById(id);} function randomInt(){ var rancor=Math.floor(Math.random()*256); return rancor; } function ChangeColor(){ table=$("FirstTab"); color=table.getAttribute("bgcolor");//保存原始值 var r=randomInt().toString(16);///转化为16进制 var g=randomInt().toString(16); var b=randomInt().toString(16); var rescolor="#"+r+g+b; table.setAttribute("bgcolor",rescolor);///把后者的值赋值给前者 } function ResetColor(){ ///color="#179BD6"; table.setAttribute("bgcolor",color); } </script> </head> <body> <form method="post" > <table align="center" border="1" bgcolor="#179BD6" width="500px" id="FirstTab"> <tr> <caption>学生花名册</caption> <td>序号</td> <td>姓名</td> <td>学号</td> <td>专业</td> </tr> <tr> <td>1</td> <td>Cutele</td> <td>261</td> <td>软件工程</td> </tr> <tr> <td>2</td> <td>小乐乐</td> <td>20192203262</td> <td>网络工程</td> </tr> <tr> <td colspan="4"> <input type="button" value="change color" onClick="ChangeColor()"> <input type="button" value="reset color" onClick="ResetColor()"> </td> </tr> </table> </form> </body> </html>
