Javascript function to display date in "since" format

since.js

function since(from, level) {
    var durationInit = sys.time - new Date(from).getTime();
    var DAYS_PER_YEAR = 365.24225;
    var M_PER_SECOND = 1000;
    var M_PER_MINUTE = 60 * M_PER_SECOND;
    var M_PER_HOUR = 60 * M_PER_MINUTE;
    var M_PER_DAY = 24 * M_PER_HOUR;
    var M_PER_WEEKS = 7 * M_PER_DAY;
    var M_PER_MONTH = Math.floor((DAYS_PER_YEAR / 12) * M_PER_DAY);
    var M_PER_YEAR = Math.floor(DAYS_PER_YEAR * M_PER_DAY);

    if (durationInit < 60000 && durationInit > -60000) {
        return getLang(durationInit > 0 ? "JUST_NOW" : "IMMEDIATELY");
    }

    var durationMillis = (durationInit > 0) ? durationInit : -durationInit;

    var years = Math.floor(durationMillis / M_PER_YEAR);
    durationMillis = durationMillis - (years * M_PER_YEAR);

    var months = Math.floor(durationMillis / M_PER_MONTH);
    durationMillis = durationMillis - (months * M_PER_MONTH);

    var weeks = Math.floor(durationMillis / M_PER_WEEKS);
    durationMillis = durationMillis - (weeks * M_PER_WEEKS);

    var days = Math.floor(durationMillis / M_PER_DAY);
    durationMillis = durationMillis - (days * M_PER_DAY);

    var hours = Math.floor(durationMillis / M_PER_HOUR);
    durationMillis = durationMillis - (hours * M_PER_HOUR);

    var minutes = Math.floor(durationMillis / M_PER_MINUTE);
    durationMillis = durationMillis - (minutes * M_PER_MINUTE);

    var seconds = Math.floor(durationMillis / M_PER_SECOND);
    durationMillis = durationMillis - (seconds * M_PER_SECOND);


    var space_num = " ";
    var space = "";
    var since = "";

    since += getLang(durationInit > 0 ? "AGO_BEFORE" : "IN_BEFORE");
    for (var i = 0; i < 6 && level > 0; i++) {
        var effect = false;
        if (years > 0) {
            since += space + years + space_num + (years > 1 ? getLang("YEARS") : getLang("YEAR"));
            years = 0;
            effect = true;
            level--;
        } else if (months > 0) {
            since += space + months + space_num + (months > 1 ? getLang("MONTHS") : getLang("MONTH"));
            months = 0;
            effect = true;
            level--;
        } else if (weeks > 0) {
            since += space + weeks + space_num + (weeks > 1 ? getLang("WEEKS") : getLang("WEEK"));
            weeks = 0;
            effect = true;
            level--;
        } else if (days > 0) {
            since += space + days + space_num + (days > 1 ? getLang("DAYS") : getLang("DAY"));
            days = 0;
            effect = true;
            level--;
        } else if (hours > 0) {
            since += space + hours + space_num + (hours > 1 ? getLang("HOURS") : getLang("HOUR"));
            hours = 0;
            effect = true;
            level--;
        } else if (minutes > 0) {
            since += space + minutes + space_num + (minutes > 1 ? getLang("MINUTES") : getLang("MINUTE"));
            minutes = 0;
            effect = true;
            level--;
        } else if (seconds > 0) {
            since += space + seconds + space_num + (seconds > 1 ? getLang("SECONDS") : getLang("SECOND"));
            seconds = 0;
            effect = true;
            level--;
        }
        if (effect) {
            if (level == 1) {
                space = " " + getLang("AND") + " ";
            } else {
                space = ", ";
            }
        }
    }

    return since + getLang(durationInit > 0 ? "AGO_AFTER" : "IN_AFTER");
}