use ago.js from cdn.rawgit.com

app/assets/javascripts/ago.js

@@ -1,89 +0,0 @@
-function Ago(nodes, options) {
-  if (!(nodes instanceof Array)) {
-    options = nodes;
-    nodes = undefined;
-  }
-  nodes = nodes || document.querySelectorAll("time");
-  options = options || {};
-
-
-  var default_opts = {
-    interval: 10000, // 10 secs
-    units: [
-      ["minute",     60],
-      ["hour",     3600],
-      ["day",     86400],
-      ["week",   604800],
-      ["month", 2592000],
-      ["year", 31536000]
-    ],
-    date: function(node) {
-      console.debug(node);
-      // works on  HTML "time" nodes
-      return new Date(node.getAttribute("datetime"));
-    },
-    format: function(time, unit) {
-      if (!unit) return "just now";
-      var tail = time < 0 ? " ahead" : " ago";
-      return Math.abs(time) + " " + unit + tail;
-    },
-    plural: {
-      minute: "minutes",
-      hour: "hours",
-      day: "days",
-      week: "weeks",
-      month: "months",
-      year: "years"
-    }
-  };
-
-  // override default options
-  for (var key in default_opts) {
-    options[key] = options[key] || default_opts[key];
-  }
-
-
-  var ago = function(node) {
-    // use callback to get date
-    var ago_date = options.date(node);
-    // get seconds ago
-    var ago_time = (new Date().getTime() - ago_date.getTime()) / 1000;
-    var abs_time = Math.floor(Math.abs(ago_time));
-
-    // find greatest unit
-    var unit = null;
-    var unit_time = null;
-    for (var u in options.units) {
-      var secs = options.units[u][1];
-      if (abs_time >= secs) {
-        unit = options.units[u][0];
-        unit_time = secs;
-      } else {
-        break;
-      }
-    }
-
-    if (unit_time !== null) {
-      abs_time = Math.floor(abs_time/unit_time);
-      // plural
-      if (abs_time != 1) {
-        unit = options.plural[unit];
-      }
-    }
-    node.textContent = options.format(ago_time < 0 ? -abs_time : abs_time, unit);
-  };
-
-
-  var update_all = function() {
-    for (var i = 0; i < nodes.length; i++) {
-      ago(nodes[i]);
-    }
-  };
-
-
-  update_all();
-  setInterval(function() {
-    update_all();
-  }, options.interval);
-
-}

app/assets/javascripts/application.js

@@ -13,6 +13,5 @@
 //= require jquery_ujs
 //= require app
 //= require editor
-//= require ago
 //= require highlight
 //= require autocomplete

app/views/layouts/application.html.erb

@@ -7,6 +7,7 @@
   <%= stylesheet_link_tag "application", :media => "all" %>
   <%= csrf_meta_tags %>
   <%= favicon_link_tag "favicon.ico" %>
+  <%= javascript_include_tag "https://cdn.rawgit.com/jomo/ago.js/master/ago.min.js" %>
   <%= javascript_include_tag "application" %>
   <link type="application/atom+xml" rel="alternate" href="<%= blogposts_path(:atom) %>">
   <%= yield(:site_headers) %>