path: root/underlays/javascript/relativedate.js

// Causes html elements in the 'relativedate' class to be displayed
// as relative dates. The date is parsed from the title attribute, or from
// the element content.

var dateElements;

hook("onload", getDates);

function getDates() {
    dateElements = getElementsByClass('relativedate');
    for (var i = 0; i < dateElements.length; i++) {
        var elt = dateElements[i];
        var title = elt.attributes.title;
        var d = new Date(title ? title.value : elt.innerHTML);
        if (! isNaN(d)) {
            dateElements[i].date=d;
            elt.title=elt.innerHTML;
        }
    }

    showDates();
}

function showDates() {
    for (var i = 0; i < dateElements.length; i++) {
        var elt = dateElements[i];
        var d = elt.date;
        if (! isNaN(d)) {
            elt.innerHTML=relativeDate(d);
        }
    }
    setTimeout(showDates,30000); // keep updating every 30s
}

var timeUnits = new Array;
timeUnits['minute'] = 60;
timeUnits['hour'] = timeUnits['minute'] * 60;
timeUnits['day'] = timeUnits['hour'] * 24;
timeUnits['month'] = timeUnits['day'] * 30;
timeUnits['year'] = timeUnits['day'] * 364;
var timeUnitOrder = ['year', 'month', 'day', 'hour', 'minute'];

function relativeDate(date) {
    var now = new Date();
    var offset = date.getTime() - now.getTime();
    var seconds = Math.round(Math.abs(offset) / 1000);

    // hack to avoid reading just in the future if there is a minor
    // amount of clock slip
    if (offset >= 0 && seconds < 30 * timeUnits['minute']) {
        return "just now";
    }

    var ret = "";
    var shown = 0;
    for (i = 0; i < timeUnitOrder.length; i++) {
        var unit = timeUnitOrder[i];
        if (seconds >= timeUnits[unit]) {
            var num = Math.floor(seconds / timeUnits[unit]);
            seconds -= num * timeUnits[unit];
            if (ret)
                ret += "and ";
            ret += num + " " + unit + (num > 1 ? "s" : "") + " ";

            if (++shown == 2)
                break;
        }
        else if (shown)
            break;
    }

    if (! ret)
        ret = "less than a minute "

    return ret + (offset < 0 ? "ago" : "from now");
}