web/_includes/timeago.html

<!--
  Date format snippet
  See: ${JS_ROOT}/utils/timeago.js
-->

{% assign tooltip_df = site.data.locales[lang].date_format.tooltip %}
{% assign post_long_df = site.data.locales[lang].date_format.post.long %}
{% assign post_short_df = site.data.locales[lang].date_format.post.short %}

<em class="timeago{% if include.class %} {{ include.class }}{% endif %}"
    date="{{ include.date }}"
    {% if include.tooltip %}
      data-toggle="tooltip"
      data-placement="bottom"
      title="{{ include.date | date: tooltip_df }}"
    {% endif %}>

  {%- assign this_year = site.time | date: "%Y" -%}
  {%- assign post_year = include.date | date: "%Y" -%}

  {%- if post_year == this_year -%}
    {{ include.date | date: post_short_df }}
  {%- else -%}
    {{ include.date | date: post_long_df }}
  {%- endif -%}
</em>