Filters

Filters are simply modules that export their methods to liquid. All methods will have to take at least one parameter which represents the input of the filter. The return value will be the output of the filter.

module Jekyll
  module AssetFilter
    def asset_url(input)
      "http://www.example.com/#{input}?#{Time.now.to_i}"
    end
  end
end

Liquid::Template.register_filter(Jekyll::AssetFilter)
ProTip™: Access the site object using Liquid

Jekyll lets you access the site object through the context.registers feature of Liquid at context.registers[:site]. For example, you can access the global configuration file _config.yml using context.registers[:site].config.