Javascript run function only once and avoid running again in refresh
<p>I am developing TimeAgo jQuery plugin that calculates time since a given datetime.
Example: 4 minutes ago</p>

<p>I developed it to be according to user`s timezone and it works ok but when it refreshs automaticly it repeats the minus/plus hours according to time zone..</p>

<p>I want to add value only once!</p>

<p>JS code:</p>

<pre><code> (function($) {
    $.timeago = function(timestamp) {
        if (timestamp instanceof Date) {
            return inWords(timestamp);
        } else if (typeof timestamp === "string") {
            return inWords($.timeago.parse(timestamp));
        } else if (typeof timestamp === "number") {
            return inWords(new Date(timestamp));
        } else {
            return inWords($.timeago.datetime(timestamp));
        }
    };
    var $t = $.timeago;

    $.extend($.timeago, {
        settings: {
            refreshMillis: 60000,
            allowFuture: false,
            strings: {
                prefixAgo: null,
                prefixFromNow: null,
                suffixAgo: "قبل",
                suffixFromNow: "من الآن",
                seconds: "اقل من دقيقة",
                minute: "دقيقة",
                minutes: "%d دقيقة",
                hour: "ساعة",
                hours: "%d ساعة",
                day: "يوم",
                days: "%d يوم",
                month: "شهر",
                months: "%d اشهر",
                year: "سنة",
                years: "%d سنين",
                wordSeparator: " ",
                numbers: []
            }
        },
        inWords: function(distanceMillis) {
            var $l = this.settings.strings;
            var prefix = $l.prefixAgo;
            var suffix = $l.suffixAgo;
            if (this.settings.allowFuture) {
                if (distanceMillis &lt; 0) {
                    prefix = $l.prefixFromNow;
                    suffix = $l.suffixFromNow;
                }
            }

            var seconds = Math.abs(distanceMillis) / 1000;
            var minutes = seconds / 60;
            var hours = minutes / 60;
            var days = hours / 24;
            var years = days / 365;

            function substitute(stringOrFunction, number) {
                var string = $.isFunction(stringOrFunction) ? stringOrFunction(number, distanceMillis) : stringOrFunction;
                var value = ($l.numbers &amp;&amp; $l.numbers[number]) || number;
                return string.replace(/%d/i, value);
            }

            var words = seconds &lt; 45 &amp;&amp; substitute($l.seconds, Math.round(seconds)) ||
        seconds &lt; 90 &amp;&amp; substitute($l.minute, 1) ||
        minutes &lt; 45 &amp;&amp; substitute($l.minutes, Math.round(minutes)) ||
        minutes &lt; 90 &amp;&amp; substitute($l.hour, 1) ||
        hours &lt; 24 &amp;&amp; substitute($l.hours, Math.round(hours)) ||
        hours &lt; 42 &amp;&amp; substitute($l.day, 1) ||
        days &lt; 30 &amp;&amp; substitute($l.days, Math.round(days)) ||
        days &lt; 45 &amp;&amp; substitute($l.month, 1) ||
        days &lt; 365 &amp;&amp; substitute($l.months, Math.round(days / 30)) ||
        years &lt; 1.5 &amp;&amp; substitute($l.year, 1) ||
        substitute($l.years, Math.round(years));

            var separator = $l.wordSeparator === undefined ? " " : $l.wordSeparator;
            return $.trim([prefix, suffix, words].join(separator));
        },
        parse: function(iso8601) {
            var s = $.trim(iso8601);
            s = s.replace(/\.\d+/, ""); // remove milliseconds
            s = s.replace(/-/, "/").replace(/-/, "/");
            s = s.replace(/T/, " ").replace(/Z/, " UTC");
            s = s.replace(/([\+\-]\d\d)\:?(\d\d)/, " $1$2"); // -04:00 -&gt; -0400
            return new Date(s);
        },
        datetime: function(elem) {
            var iso8601 = $t.isTime(elem) ? $(elem).attr("datetime") : $(elem).attr("title");
            return $t.parse(iso8601);
        },
        isTime: function(elem) {
            // jQuery's `is()` doesn't play well with HTML5 in IE
            return $(elem).get(0).tagName.toLowerCase() === "time"; // $(elem).is("time");
        }
    });

    $.fn.timeago = function() {
        var self = this;
        self.each(refresh);

        var $s = $t.settings;
        if ($s.refreshMillis &gt; 0) {
            setInterval(function() { self.each(refresh); }, $s.refreshMillis);
        }
        return self;
    };

    function refresh() {
        var data = prepareData(this);
        var dt = data.datetime;
        if (!isNaN(dt)) {
            $(this).text(inWords(dt));
        }
        return this;
    }

    function prepareData(element) {
        element = $(element);
        if (!element.data("timeago")) {
            element.data("timeago", { datetime: $t.datetime(element) });
            var text = $.trim(element.text());
            if (text.length &gt; 0 &amp;&amp; !($t.isTime(element) &amp;&amp; element.attr("title"))) {
                element.attr("title", text);
            }
        }
        return element.data("timeago");
    }

    function get_time_zone_offset() {
        var current_date = new Date();
        return -current_date.getTimezoneOffset() / 60;

    }

    function inWords(date) {
        date.setHours(date.getHours() + get_time_zone_offset());
        return $t.inWords(distance(date));
    }

    function distance(date) {
        return (new Date().getTime() - date.getTime());
    }

    // fix for IE6 suckage
    document.createElement("span");
    document.createElement("time");
} (jQuery));
</code></pre>
