字符串:var s = "1,2,3,4,5," 目标:删除最后一个 "," 方法:s=s.substring(0,s.Length-1); 字符串:var s2 = "img/upload/123.jpg" 目标:获取文件名(不包含后缀名) 方法:s2=s2.substring(s2.lastIndexOf('/')+1, s2.lastIndexOf('.'));