字串：var s = "1,2,3,4,5," 目標：刪除最後一個 "," 方法：s=s.substring(0,s.Length-1)； 字串：var s2 = "img/upload/123.jpg" 目標：取得檔案名稱(不包含後綴名) 方法：s2=s2.substring(s2.lastIndexOf('/') 1, s2.lastIndexOf('.'));
