javascriptのurlパラメータparseとbuild関数

    function getParam() {
        var param = new Object()
        var item = new Array();
        if (location.search == "") {
            return param;
        };
        var query = location.search.substring(1);                                                                                                                                      
        var list = query.split('&');
        for(var i = 0; i < list.length; i++) {
            item = list[i].split('=');
            if (typeof param[item[0]] == "undefined") {
                param[item[0]] = new Array();
            }
            param[item[0]].push(item[1]);
        };
        return param;
    };

    function getUrlByParam(param) {
        var url = "";
        for (field in param) {
            for (index in param[field]) {
                url += "&" + field + "=" + param[field][index];
            };
        };
        return url == "" ? url : url.substring(1);
    };