util=function(){
    return {
        $:function(id){
            return document.getElementById(id);
        },
        trim:function(str){
            return str.replace(/(^\s+)|(\s+$)/g, "");
        },
        len:function(str){   
            return str.replace(/[^\x00-\xff]/g,‘**‘).length;   
        },
        format:function(str){
            var arg = arguments;
            return str.replace(/\{(\d+)\}/g, function(m, i){
                return arg[parseInt(i)+1];
            });
        },
        each:function(object, callback, args){
            var name, i = 0, length = object.length;
            if ( args ) {
                if ( length === undefined ) {
                    for ( name in object )
                        if ( callback.apply( object[ name ], args ) === false )
                            break;
                } else
                    for ( ; i < length; )
                        if ( callback.apply( object[ i++ ], args ) === false )
                            break;
            } else {
                if ( length === undefined ) {
                    for ( name in object )
                        if ( callback.call( object[ name ], name, object[ name ] ) === false )
                            break;
                } else
                    for ( var value = object[0];
                        i < length && callback.call( value, i, value ) !== false; value = object[++i] ){}
            }
        },
        setCookie:function(name,value,hours,path,domain){
            var str=new String();
            var nextTime=new Date();
            nextTime.setHours(nextTime.getHours()+hours);
            str=name+"="+escape(value);
            if(hours)
                str+=";expires="+nextTime.toGMTString();
            if(path)
                str+=";path="+path;
            if(domain)
                str+=";domain="+domain;
            document.cookie=str;
        },
        getCookie:function(name){
            var rs=new RegExp("(^|)"+name+"=([^;]*)(;|$)","gi").exec(document.cookie),tmp;
            if(tmp=rs)
                return unescape(tmp[2]);
            return null;
        },
        delCookie:function(name){
            document.cookie = name + "=-1" + "; expires=Fri, 31 Dec 1999 23:59:59 GMT;";
        },
        /**
        *url String
        *parms String
        *method String default value "get"
        *asy Boolean defalut value true
        *success Function(http_request.responseText)
        **/
        ajax:function(config){
            var url=config.url,
                parms=(config.parms?config.parms:"") + "&t="+new Date().getTime(),
                method=config.method||"get",
                asy=true;
            var http_request=null;

            if(method.toLowerCase()=="get"){
                url=url+"?"+parms;
                parms=null;
            }

            //开始初始化XMLHttpRequest对象
            if(window.XMLHttpRequest) { //Mozilla 浏览器
                http_request = new XMLHttpRequest();
                if (http_request.overrideMimeType) {//设置MiME类别
                    http_request.overrideMimeType("text/xml");
                }
            } else if (window.ActiveXObject) { // IE浏览器
                try {
                    http_request = new ActiveXObject("Msxml2.XMLHTTP");
                } catch (e) {
                    try {                
                        http_request = new ActiveXObject("Microsoft.XMLHTTP");
                    } catch (e) {}
                }
            }
            if(!http_request) { // 异常，创建对象实例失败
                throw new Error("不能创建XMLHttpRequest对象实例.");
                return null;
            }
            http_request.open(method,url,asy);

            http_request.onreadystatechange=function(){
                if (http_request.readyState == 4){
                    try{
                        if (http_request.status == 200){
                            config.success(http_request.responseText);
                        }
                    }catch(e){
                        throw new Error("数据读取失败.");
                    }
                }
            };
            if(method.toLowerCase()=="post"){
                http_request.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
            }
            http_request.send(parms);
        }
    };
}();

我写的javascript常用静态方法类，分享给大家