<HTML>
<BODY topmargin='2' leftmargin='2'>
<BASE target='_top'><SCRIPT language='Jscript'>
function fun1(){
var str ='ssabababa';
var tt = str.replace('b','-').replace('b','-').search('b');
alert(tt);}
</SCRIPT><input type='button' onclick='fun1();' value='test' name='bt'>
</BODY>
</HTML>
var str = "abababab";
var i = 0;
var index = -1;
while (i<3)
{
index = str.indexOf("b", index + 1);
i++;
}
alert("第三个 b 出现在字符串的第 "+ index +" 位上");
</SCRIPT>