ie6不支持jquery的trim()方法,于是找来这个代码备用
>>> "sss".replace(/^\s+|\s+$/g, "")
"sss"
>>> " sss".replace(/^\s+|\s+$/g, "")
"sss"
>>> " sss ".replace(/^\s+|\s+$/g, "")
"sss"
>>> " s s s ".replace(/^\s+|\s+$/g, "")
"s s s"