How can I check if a string ends with a particular substring in Liquid?

Question

I know there is a contains keyword so I can use:

{% if some_string contains sub_string %}
    <!-- do_something -->
{% ... %}

But how can I check if a string ends with a particular substring?

I've tried this but it won't work:

{% if some_string.endswith? sub_string %}
    <!-- do_something -->
{% ... %}

Haley

Answer 1

As a workaround you could use the string slice method

• with as startIndex: some_string length - sub_string length and
• stringLength: sub_string size
• and if the result of the slice is the same as the sub_string -> the sub_string is at the end of some_string.

it's a bit clumpy in a liquid template but it would look like:

{% capture sub_string %}{{'subString'}}{% endcapture %}
{% capture some_string %}{{'some string with subString'}}{% endcapture %}

{% assign sub_string_size = sub_string | size %}
{% assign some_string_size = some_string | size %}
{% assign start_index = some_string_size | minus: sub_string_size %}
{% assign result = some_string | slice: start_index, sub_string_size %}

{% if result == sub_string %}
    Found string at the end
{% else %}
    Not found
{% endif %}

and if the some_string is empty or shorter than sub_string it works anyway because the slice result would be empty as well

Warford

Why are you using capture instead of assign ? – Bloodshot

I am not sure actually. Here it says capture is/can be faster in some cases. I think capture makes sense for the some_string and sub_string definition because it could be something constructed from other things. Perhaps for the rest assign would be clearer to read. What do you think? – Warford

In your case, with no append, like in {% assign foobar = "foo" | append: bar %}, the assign is 20% faster. From my point of view, when you can do with assign, this avoid you errors with unwanted spaces or line breaks. – Bloodshot

Haven't tried this answer. I use other approach and avoided to check string endings in liquid code. – Haley

Answer 2

With Jekyll, I ended up writing a small module-wrapper that adds a filter:

module Jekyll
   module StringFilter
    def endswith(text, query)
      return text.end_with? query
    end
  end
end
  
Liquid::Template.register_filter(Jekyll::StringFilter)

I use it like this:

{% assign is_directory = page.url | endswith: "/" %}

Vasty

Docs on installing/creating plugins: jekyllrb.com/docs/plugins/installation – Stubbs

Answer 3

We can use another solution with split filter.

{%- assign filename = 'main.js' -%}
{%- assign check = filename | split:'js' -%}

{% if check.size == 1 and checkArray[0] != filename %}
   Found 'js' at the end
{% else %}
   Not found 'js' at the end
{% endif %}

Here we go ^^.

Coleman

No, this is wrong ie. "mainjson.js" will fail in the first condition but does indeed end with "js" – Harrumph

Answer 4

Expanding the answer by @v20100v

It would be best to get the last item in the array after splitting, as the string may have multiple occurrences of the separator,
e.g. "test_jscript.min.js".

Something like the below:

{% assign check = filename | split:'.' | last %}

{% if check == "js" %}
    Is a JS file
{% else %}
    Is not a JS file
{% endif %}

Trichome