方法一（正则表达式）：

    function getQueryString(name) {  
        var reg = new RegExp("(^|&)" + name + "=([^&]*)(&|$)", "i");  
        var r = window.location.search.substr(1).match(reg);  
        if (r != null) return unescape(r[2]); return null;  
    }  
  
    var from = getQueryString("from");  
  
    alert(from);  

方法二（截取、分割字符串）：

    function GetRequest() {   
        var url = location.search; //获取url中"?"符后的字串   
        var theRequest = new Object();   
        if (url.indexOf("?") != -1) {  
            var str = url.substr(1);   
            strs = str.split("&");   
            for(var i = 0; i < strs.length; i ++) {  
                theRequest[strs[i].split("=")[0]]=unescape(strs[i].split("=")[1]);   
            }   
        }   
        return theRequest;   
    }   
  
    var req = GetRequest();   
  
    var from = req['from'];  
  
    alert(from);