0.0.2 • Public • Published

Eleventy Plugin i18n Helpers

Internationalization helpers for 11ty, including filters and data cascade for localized content.


This plugin comes with three filters, date, localeURL, and langName.


Formats a date using Date.toLocaleDateString. May require including full-icu in your project; the filter will detect if it's needed and throw an error if it is.

Usage, default

{{'January 1, 2022' | date}}
<!-- 1/1/2022 -->

Usage, advanced

{{'January 1, 2022' | date('es', {weekday: 'long'})}}
<!-- sábado -->


  • defaultLocale - Default locale to use for formatting. Defaults to en-US. Shared with localeURL filter.
  • defaultFormat - Default formatting options to use. Defaults to {};


Formats an locale-specific path /en/foo/bar and updates it to use the provided locale. Accepts either URL objects or strings in the form of a URL pathname.


{{ '/en/foo/bar' | localeURL('es')}}
<!-- /es/foo/bar -->


  • defaultLocale - Default locale to use for formatting. Defaults to en-US. Shared with date filter.


Exposes the iso-639-1 module, allowing you to access information about countries like their names, languages, codes, and validate country codes. To use, pass in the method you want to the filter.

Sample Usage

{{'de' | iso('getName')}}
<!-- German -->

Data Fallback

The Data Fallback helper is advanced functionality to allow data from one folder to fall back to another, for instance a localization's data to fall back to the site default language's data. This allows data changes, like localization, to be done progressively without requiring additional logic or complexity in your templating to ensure the data objects you expect to be available are, in fact, there. As an added bonus, it allows data for data to be stored across multiple files and in JSON, JS, or YAML format, making it easier to maintain.

This function requires a (somewhat) specific folder structure, as follows:

|- content root
  |- folder-1
    |- folder-1.11tydata.js
    |- _data
      |- my-data.{json|js|yml|yaml}
  |- folder-2
    |- folder-2.11tydata.js
    |- _data
      |- my-data.{json|js|yml|yaml}

All localized content, including your default language, if you have one, should be stored inside a "content root" folder (the actual folder name is irrelevant, it could be your project root, it could be another folder, it just matters that all related folders are stored together). Inside each folder, you need to include an 11tydata.js file, named the same thing as the folder it's in, which would look something like this for folder-2:

// folder-2.11tydata.js
const dataFallback = require('eleventy-plugin-i18n-helpers/data-fallback');

module.exports = function() {
  return dataFallback('folder-1');

You also need to include a _data folder; place your data in there! Each file in that folder can be a .json, .js, .yaml, or .yml file, with the filename becoming the data key and the exported values being sub-keys, so a file named name.yml and a property named first would be available in 11ty as name.first. When any of those files are changed, 11ty will rebuild and update your data.

The fallback works by finding all of data files in a folder's _data folder and comparing it with the files in the fallback's _data folder. Any files present in the fallback but not in the original folder will be used to build the original folder's data object.

Once this is set up, you also need to pass the contentRoot option to the plugin, set to the path of your content root. You can also optionally pass in a fallbackFolders option, which is an array of folder names to watch for changes to. It defaults to all ISO6391 country codes.


As an example for how to set this up for localization, you may have a folder structure as follows:


|- pages
  |- de
    |- de.11tydata.js
    |- _data
      |- home.json
      |- menu.yaml
  |- en
    |- en.11tydata.js
    |- _data
      |- home.json
  |- es
    |- es.11tydata.js
    |- _data
      |- menu.yaml


const dataFallback = require('eleventy-plugin-i18n-helpers/data-fallback');

module.exports = function() {
  return dataFallback('de');



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