js如何在指定位置插入字符 最好是正则

Question

问题一：
var str="/project/administrator/manage/images/20120917434553.jpg";
请用jquery 将此字符串变为"/project/administrator/manage/images/d20120917434553.jpg"
就是说在最后一个"/"后面加个字符
问题二：将此字符串的文件名输出，也就是说要得到的结果是"20120917434553.jpg";
多谢各位

Answer 1

var str='/project/administrator/manage/images/20120917434553.jpg';
var arr = str.split('/');
alert(arr[arr.length-1])
arr[arr.length-1] = 'd'+arr[arr.length-1];
str = arr.join('/');
alert(str)

Answer 2

var str="/project/administrator/manage/images/20120917434553.jpg";
var reg = /([^\/]+)$/g;
str = str.replace(reg,'d$1');
document.writeln(str);
document.writeln(RegExp.$1);

Answer 3

<script language="javascript">
var str="/project/administrator/manage/images/20120917434553.jpg";
var nm1=str.lastIndexOf("/");
var str2=str.substr(0,nm1+1)+"d"+str.substr(nm1+1,str.length-nm1);
var str3=str.substr(nm1+1,str.length-nm1);
alert(str2);
alert(str3);
</script>

Answer 4

var str="/project/administrator/manage/images/20120917434553.jpg",
reg = /\/([^/]+)$/
fileName = reg.exec(str)[1];
str = str.replace(reg, "\/d$1");

Answer 5

var str="/project/administrator/manage/images/20120917434553.jpg",
reg = /\/([^/]+)$/,
fileName = reg.exec(str)[1];
str = str.replace(reg, "\/d$1");