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('.') );