String.prototype.startsWith = function(str){
    return (this.indexOf(str) === 0);
};

function isEmpty(str) {
    if (str == null || str.length == 0) {
        return true;
    } else {
        return false;
    }
}

function replaceNewLineToBr(contents) {
	var result = contents.replace(/\n/g, "<br />");
	return result;
}

Number.prototype.fillZero = function(n) {
    var r = this.toString().split('');
    while(r.length < n) {
        r.unshift('0');
    }
    return r.join('');
};

function now() {
	return (new Date).getTime();
}

function computeDate(year, month, day, addDays) {
    var dt = new Date(year, month - 1, day);
    var baseSec = dt.getTime();
    var addSec = addDays * 86400000;
    var targetSec = baseSec + addSec;
    dt.setTime(targetSec);
    return dt;
}

function autolink_url(str) {
    return str.replace(/(http:\/\/[\x21-\x7e]+)/gi, '<a href="$1" target="_blank">$1</a>');
}