js 根据 改变菜单 属性

<script type="text/javascript">
                    window.onload=function(){
                        
                    var box = document.getElementById('abox');
                    var alinks = box.getElementsByTagName('a');
                    for (var i = 0; i < alinks.length; i++) {
                        alinks[i].setAttribute("class","");
                    }
                    var id=0;
                    var parameter = getPar('a');
                    switch(parameter)
                    {
                        case 'postidea' : 
                        case 'buyidea' :
                        case 'mysale' :
                            id = 1;
                            break;
                        case 'mygift':
                        case 'sendgift':
                            id = 2;
                            break;
                        case 'updatetelphone':
                        case 'updateprofile' :
                        case 'updatepass' :
                        case 'updateavatar' :
                            id = 3;
                            break;
                        case 'alipay' :
                        case 'payin' :
                        case 'payout' :
                            id = 4;
                            break;
                        default:
                            id = 0;
                            break;
                    }
                    // whichLink.setAttribute("class","selected");
                    alinks[id].setAttribute("class","selected");
                }
                function getPar(par){
                    //获取当前URL
                    var local_url = document.location.href; 
                    //获取要取得的get参数位置
                    var get = local_url.indexOf(par +"=");
                    if(get == -1){
                        return false;   
                    }   
                    //截取字符串
                    var get_par = local_url.slice(par.length + get + 1);    
                    //判断截取后的字符串是否还有其他get参数
                    var nextPar = get_par.indexOf("&");
                    if(nextPar != -1){
                        get_par = get_par.slice(0, nextPar);
                    }
                    return get_par;
                }
                </script>