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javaScript:製作隨機驗證碼
第一步：製作10張圖片，上面亂畫些字母當然你可要記下來你每張圖上的內容阿！！這些圖取名1.jpg,2.jpg...0.jpg
第二步：
這些代碼寫在<head><script></script></head>之間：
function check_rand()//檢查用的
{
var rand_test;
rand_test=document.form1.rand_test.value.trim();
if (rand_test.length==0)
{alert('請填寫驗證碼。'); return false;}
else if (rand_test==document.random_value)
return true;
else
{alert('驗證碼填寫錯誤。'); return false;}
}
//下面是產生隨機數
function rnd()
{
var today=new Date();
var seed=today.getTime();
seed = (seed*9301+49297) % 233280;
return seed/(233280.0);
}
function rand(number)
{
return Math.ceil(rnd()*number);
}
//下面是顯示圖片：
function show_code()
{
var i,num;
var pic;
var tag;
document.random_value=""
num=rand(10);
switch(num)
{
case 1:pic="1";tag="1A43";break;
case 2:pic="2";tag="50J7";break; //圖片所對應的字母序列
case 3:pic="3";tag="8900";break;
case 4:pic="4";tag="LU0E";break;
case 5:pic="5";tag="7727";break;
case 6:pic="6";tag="Y943";break;
case 7:pic="7";tag="35B1";break;
case 8:pic="8";tag="24P6";break;
case 9:pic="9";tag="M76M";break;
case 10:pic="0";tag="8LX5";break;
}
document.random_value=tag;
document.form1.img0.src="code/"+pic+".JPG";
}
第三步 在網頁中顯示它
<body >
...
<td height="26"><div align="right" >驗證碼：</div></td>
<td colspan="3"><input type="text" size="5" maxlength="4">
<img src="" width="100" height="32" alt=""> </td>
...
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