随机广告图片

<script language="JavaScript">
a = 3
var slump = Math.random();
var talet = Math.round(slump * (a-1))+1;
function create() {
        this.src = ''
        this.border = ''
 this.alt = ''
 
}

b = new Array()
for(var i=1; i<=a; i++) { b[i] = new create() }

b[1].src    = "../pic/pic01.gif"
b[1].border = "0"
b[1].alt    = "图形一"

b[2].src    = "../pic/pic02.gif"
b[2].border = "0"
b[2].alt    = "图形二"

b[3].src    = "../pic/pic03.gif"
b[3].border = "0"
b[3].alt    = "图形三"

var visa = "";

visa += '<img src='+b[talet].src+' border="0"'+' alt='+b[talet].alt+'>';
</script>
<script language="JavaScript">
<!-- Hide this script from old browsers --
document.write(visa)
// -->
</script>

来源：https://www.cnblogs.com/pageantry/archive/2007/03/27/689515.html