Note some js date time

// Compute diff datetime
// Don't know why fetch from MySQL query become Date JS object without convert.

 var last_activity = result_find_usr_by_id[0].updated_at;
console.log('last ' + last_activity);
var oneDay = 24*60*60*1000; // hours*minutes*seconds*milliseconds
var todayDate = new Date();
console.log('today ' + todayDate);

var diffDays = 0;
if(typeof last_activity !== 'undefined') {
    // Split timestamp into [ Y, M, D, h, m, s ]
    // var t = last_activity.split(/[- :]/);

    // Apply each element to the Date function
    // var last_activity = new Date(Date.UTC(t[0], t[1]-1, t[2], t[3], t[4], t[5]));

    var diffDays = Math.round(Math.abs((last_activity.getTime() - todayDate.getTime())/(oneDay)));
        console.log('diff '+ diffDays);
     }


/**
 * You first need to create a formatting function to pad numbers to two digits…
 **/
function twoDigits(d) {
    if(0 <= d && d < 10) return "0" + d.toString();
    if(-10 < d && d < 0) return "-0" + (-1*d).toString();
    return d.toString();
}

/**
 * …and then create the method to output the date string as desired.
 * Some people hate using prototypes this way, but if you are going
 * to apply this to more than one Date object, having it as a prototype
 * makes sense.
 **/
Date.prototype.toMysqlFormat = function() {
    return this.getUTCFullYear() + "-" + twoDigits(1 + this.getUTCMonth()) + "-" + twoDigits(this.getUTCDate()) + " " + twoDigits(this.getUTCHours()) + ":" + twoDigits(this.getUTCMinutes()) + ":" + twoDigits(this.getUTCSeconds());
};

https://stackoverflow.com/questions/3075577/convert-mysql-datetime-stamp-into-javascripts-date-format
https://stackoverflow.com/questions/2627473/how-to-calculate-the-number-of-days-between-two-dates