Jekyll Mark Old Posts

This post is more than 18 months old. Since technology changes to rapidly, this content may be out of date (but that's not always the case). Please remember to verify any technical or programming information with the current release.

With technology changing so rapidly and people in such a big hurry, sometimes older suggestions or out of date recommendations are the first things that programmers run into. You know you’ve fallen for it - a quick google search and you get your first result and you give it a shot; never mind that it’s a blog entry from 7 years ago.

Now, I would argue that that’s your fault - you should be keeping an eye on the date. But, I’ve decided that the best thing to do for visitors is to remind them that this content is older.

When I was using WordPress, I made a plugin called Label Old Posts - but now I use Jekyll for my blog. I could go the route of making a plugin, but you’d still have to use some sort of ‘shortcode’ type syntax to get the notification in the proper location in your theme. Instead, I decided to just add code to my post template.

Here’s the liquid code:

{% capture now %}{{'now' | date: '%s'}}{% endcapture %}  
{% capture postDate %}{{page.date | date: '%s'}}{% endcapture %}  
{% assign difference = now | minus: postDate %}  
{% if difference > 47340000 %}  
  <div class="old-post">  
    This post is more than 18 months old. Since technology changes to rapidly, 
    this content <em>may</em> be out of date (but that's not always the case).  
    Please remember to verify any technical or programming information
    with the current release.
  </div>  
{% endif %}

First, capture the current date and the post date as unix timestamps. Then, do a calculation to figure out the difference. I’m using a separate variable here because it makes it easier to do math, comparison, and it converts nicely to an integer from a string. Finally, compare the difference to the number of seconds in 18 months. If the difference is greater, display a message.

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