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Jekyll & Liquid

Leszek Pietrzak

Running

Running a local server for testing purposes:

jekyll serve
jekyll serve --watch --baseurl ''

Creating a final outcome (or for testing on a server):

jekyll build
jekyll build -w

The -w or --watch flag is for enabling auto-regeneration, the --baseurl '' one is useful for server testing.

Troubleshooting

On Windows you can get this error when building/serving:

Liquid Exception: incompatible character encodings: UTF-8 and IBM437 in index.html

You need to set the code-page first:

chcp 65001

Liquid

Output

Simple example of Output:

Hello {{name}}
Hello {{user.name}}
Hello {{ 'leszek' }}

Filtering output:

Word hello has {{ 'hello' | size }} letters!
Todat is {{ 'now' | date: "%Y %h" }}

Useful where filter example of getting single item from _data:

{% assign currentItem = site.data.foo | where:"slug","bar" %}
{{ newArray[0].name }}

Most common filters:

  • where – select elements from array with given property value: {{ site.posts | where:"category","foo" }}
  • group_by – group elements from array by given property: {{ site.posts | group_by:"category" }}
  • markdownify – convert markdown to HTML
  • jsonify – convert data to JSON: {{ site.data.dinosaurs | jsonify }}
  • date – reformat a date (syntax reference)
  • capitalize – capitalize words in the input sentence
  • downcase – convert an input string to lowercase
  • upcase – convert an input string to uppercase
  • first – get the first element of the passed in array
  • last – get the last element of the passed in array
  • join – join elements of the array with certain character between them
  • sort – sort elements of the array: {{ site.posts | sort: 'author' }}
  • size – return the size of an array or string
  • strip_newlines – strip all newlines (\n) from string
  • replace – replace each occurrence: {{ 'foofoo' | replace:'foo','bar' }}
  • replace_first – replace the first occurrence: {{ 'barbar' | replace_first:'bar','foo' }}
  • remove – remove each occurrence: {{ 'foobarfoobar' | remove:'foo' }}
  • remove_first – remove the first occurrence: {{ 'barbar' | remove_first:'bar' }}
  • truncate – truncate a string down to x characters
  • truncatewords – truncate a string down to x words
  • prepend – prepend a string: {{ 'bar' | prepend:'foo' }}
  • append – append a string: {{ 'foo' | append:'bar' }}
  • minus, plus, times, divided_by, modulo – working with numbers: {{ 4 | plus:2 }}
  • split – split a string on a matching pattern: {{ "a~b" | split:~ }}

Tags

Tags are used for the logic in your template.

Comments

For swallowing content.

We made 1 million dollars {% comment %} in losses {% endcomment %} this year

Raw

Disables tag processing.

{{ "{% raw " }}%}
    In Handlebars, {{ this }} will be HTML-escaped, but {{{ that }}} will not.
{{ "{% endraw " }}%}

If / Else

Simple expression with if/unless, elsif [sic!] and else.

{% if user %}
    Hello {{ user.name }}
{% elsif user.name == "The Dude" %}
    Are you employed, sir?
{% else %}
    Who are you?
{% endif %}
{% unless user.name == "leszek" and user.race == "human" %}
    Hello non-human non-leszek
{% endunless %}
# array: [1,2,3]
{% if array contains 2 %}
    array includes 2
{% endif %}

Case

For more conditions.

{% case condition %}
    {% when 1 %}
        hit 1
    {% when 2 or 3 %}
        hit 2 or 3
    {% else %}
        don't hit
{% endcase %}

For loop

Simple loop over a collection:

{% for item in array %}
    {{ item }}
{% endfor %}

Simple loop with iteration:

{% for i in (1..10) %}
    {{ i }}
{% endfor %}

There are helper variables for special occasions:

  • forloop.length – length of the entire for loop
  • forloop.index – index of the current iteration
  • forloop.index0 – index of the current iteration (zero based)
  • forloop.rindex – how many items are still left?
  • forloop.rindex0 – how many items are still left? (zero based)
  • forloop.first – is this the first iteration?
  • forloop.last – is this the last iteration?

Limit and offset starting collection:

# array: [1,2,3,4,5,6]
{% for item in array limit:2 offset:2 %}
    {{ item }}
{% endfor %}

You can also reverse the loop:

{% for item in array reversed %}
...
{% endfor %}

Storing variables

Storing data in variables:

{% assign name = 'leszek' %}

Combining multiple strings into one variable:

{% capture full-name %}{{ name }} {{ surname }}{% endcapture %}

Permalinks are constructed with a template:

/:categories/:year/:month/:day/:title.html

These variables are available:

  • year – year from the filename
  • short_year – same as above but without the century
  • month – month from the filename
  • i_month – same as above but without leading zeros
  • day – day from the filename
  • i_day – same as above but without leading zeros
  • title – title from the filename
  • categories– specified categories for the post