js去除左右两边空格，提取自jquery trim函数，绝对好用

 String.prototype.trim = function(){
  rtrim = /^[\s\uFEFF\xA0]+|[\s\uFEFF\xA0]+$/g ;
  return this == ""||this== null?"" :( this + "" ).replace( rtrim, "" );   
 }

使用方法

var str = "  abc  ";
var newStr = str.trim();