字符串:var s = "1,2,3,4,5,"
目標:刪除最後一個 ","
方法:s=s.substring(0,s.Length-1);
字符串:var s2 = "img/upload/123.jpg"
目標:獲取文件名(不包含後綴名)
方法:s2=s2.substring(s2.lastIndexOf('/')+1, s2.lastIndexOf('.'));