1. 去掉字符串两端的空格

String.prototype.trim=function (){return this.replace(/(^/s*)|(/s*$)/g,'');}

2. 去掉字符串中所有的空格:
 
String.prototype.sTrim = function (){return this.replace(//s/g, '');}

或者:

var s = "asd ddd bbb sss";
var reg = //s/g;
var ss = s.replace(reg, "");
alert(ss);