use timeago.js to dynamically update build timestamps

app/views/layouts/builds.html.haml

@@ -1,6 +1,6 @@
 - content_for(:head) do
   = stylesheet_link_tag 'projects'
-  = javascript_include_tag 'jquery.pjax', 'projects'
+  = javascript_include_tag 'jquery.pjax', 'jquery.timeago', 'projects'
 
 - @title = "Goldberg - #{@project.name}"
 
@@ -14,7 +14,7 @@
           - if build.revision
             %span.revision= build.revision.slice(0, 6)
           - if build.timestamp
-            = format_timestamp(build.timestamp)
+            %span.timeago(title="#{build.timestamp.iso8601}")
           %span.build-pointer
 
   .latest-build.clearfix= yield

public/javascripts/jquery.timeago.js

@@ -0,0 +1,141 @@
+/*
+ * timeago: a jQuery plugin, version: 0.9.2 (2010-09-14)
+ * @requires jQuery v1.2.3 or later
+ *
+ * Timeago is a jQuery plugin that makes it easy to support automatically
+ * updating fuzzy timestamps (e.g. "4 minutes ago" or "about 1 day ago").
+ *
+ * For usage and examples, visit:
+ * http://timeago.yarp.com/
+ *
+ * Licensed under the MIT:
+ * http://www.opensource.org/licenses/mit-license.php
+ *
+ * Copyright (c) 2008-2010, Ryan McGeary (ryanonjavascript -[at]- mcgeary [*dot*] org)
+ */
+(function($) {
+  $.timeago = function(timestamp) {
+    if (timestamp instanceof Date) return inWords(timestamp);
+    else if (typeof timestamp == "string") return inWords($.timeago.parse(timestamp));
+    else return inWords($.timeago.datetime(timestamp));
+  };
+  var $t = $.timeago;
+
+  $.extend($.timeago, {
+    settings: {
+      refreshMillis: 60000,
+      allowFuture: false,
+      strings: {
+        prefixAgo: null,
+        prefixFromNow: null,
+        suffixAgo: "ago",
+        suffixFromNow: "from now",
+        seconds: "less than a minute",
+        minute: "about a minute",
+        minutes: "%d minutes",
+        hour: "about an hour",
+        hours: "about %d hours",
+        day: "a day",
+        days: "%d days",
+        month: "about a month",
+        months: "%d months",
+        year: "about a year",
+        years: "%d years",
+        numbers: []
+      }
+    },
+    inWords: function(distanceMillis) {
+      var $l = this.settings.strings;
+      var prefix = $l.prefixAgo;
+      var suffix = $l.suffixAgo;
+      if (this.settings.allowFuture) {
+        if (distanceMillis < 0) {
+          prefix = $l.prefixFromNow;
+          suffix = $l.suffixFromNow;
+        }
+        distanceMillis = Math.abs(distanceMillis);
+      }
+
+      var seconds = 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 && $l.numbers[number]) || number;
+        return string.replace(/%d/i, value);
+      }
+
+      var words = seconds < 45 && substitute($l.seconds, Math.round(seconds)) ||
+        seconds < 90 && substitute($l.minute, 1) ||
+        minutes < 45 && substitute($l.minutes, Math.round(minutes)) ||
+        minutes < 90 && substitute($l.hour, 1) ||
+        hours < 24 && substitute($l.hours, Math.round(hours)) ||
+        hours < 48 && substitute($l.day, 1) ||
+        days < 30 && substitute($l.days, Math.floor(days)) ||
+        days < 60 && substitute($l.month, 1) ||
+        days < 365 && substitute($l.months, Math.floor(days / 30)) ||
+        years < 2 && substitute($l.year, 1) ||
+        substitute($l.years, Math.floor(years));
+
+      return $.trim([prefix, words, suffix].join(" "));
+    },
+    parse: function(iso8601) {
+      var s = $.trim(iso8601);
+      s = s.replace(/\.\d\d\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 -> -0400
+      return new Date(s);
+    },
+    datetime: function(elem) {
+      // jQuery's `is()` doesn't play well with HTML5 in IE
+      var isTime = $(elem).get(0).tagName.toLowerCase() == "time"; // $(elem).is("time");
+      var iso8601 = isTime ? $(elem).attr("datetime") : $(elem).attr("title");
+      return $t.parse(iso8601);
+    }
+  });
+
+  $.fn.timeago = function() {
+    var self = this;
+    self.each(refresh);
+
+    var $s = $t.settings;
+    if ($s.refreshMillis > 0) {
+      setInterval(function() { self.each(refresh); }, $s.refreshMillis);
+    }
+    return self;
+  };
+
+  function refresh() {
+    var data = prepareData(this);
+    if (!isNaN(data.datetime)) {
+      $(this).text(inWords(data.datetime));
+    }
+    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 > 0) element.attr("title", text);
+    }
+    return element.data("timeago");
+  }
+
+  function inWords(date) {
+    return $t.inWords(distance(date));
+  }
+
+  function distance(date) {
+    return (new Date().getTime() - date.getTime());
+  }
+
+  // fix for IE6 suckage
+  document.createElement("abbr");
+  document.createElement("time");
+})(jQuery);

public/javascripts/projects.js

@@ -23,4 +23,6 @@ $(document).ready(function() {
   });
 
   $('.build a').click(loadWithPjax);
+
+  $('.timeago').timeago();
 });