/* string */
string.prototype.remove = function (start, length) {
    var l = this.slice(0, start);
    var r = this.slice(start + length);
    return l + r;
};
string.prototype.trim = function (str) {
    if (str == null) {
        return "";
    } else {
        return str.replace(/(^\s*)|(\s*$)/g, "");
    }
};

/* datetime*/
date.prototype.format = function (format) {
    var o = {
        "m+": this.getmonth() + 1, //month
        "d+": this.getdate(), //day
        "h+": this.gethours(), //hour
        "m+": this.getminutes(), //minute
        "s+": this.getseconds(), //second
        "q+": math.floor((this.getmonth() + 3) / 3), //quarter
        "s": this.getmilliseconds() //millisecond
    };
    if (/(y+)/.test(format))
        format = format.replace(regexp.$1, (this.getfullyear() + "").substr(4 - regexp.$1.length));
    for (var k in o)
        if (new regexp("(" + k + ")").test(format))
            format = format.replace(regexp.$1,
                regexp.$1.length == 1 ? o[k] : ("00" + o[k]).substr(("" + o[k]).length));
    return format;
};