Replace absoluteUrl filter with canonicalUrl filter

README.md

@@ -11,7 +11,7 @@ You’re welcome to use the plugin even if your service isn’t considered part
 
 ## Requirements
 
-- [Node.js](https://nodejs.org) v18 or later
+- [Node.js](https://nodejs.org) v18.17 or later
 - [Eleventy](https://www.11ty.dev) v2 or later
 
 ## Installation

docs/get-started.md

@@ -23,7 +23,7 @@ This plugin includes the following features:
 
 ## Requirements
 
-- [Node.js](https://nodejs.org) v18 or later
+- [Node.js](https://nodejs.org) v18.17 or later
 - [Eleventy](https://www.11ty.dev) v2.0.0 or later
 
 [Node version manager](https://github.com/nvm-sh/nvm) is recommended if you are working across multiple projects that use different versions of Node.js.

eleventy.config.js

@@ -17,9 +17,9 @@ module.exports = function (eleventyConfig) {
       url: 'https://x-govuk.github.io/#projects',
       name: 'X-GOVUK projects'
     },
-    url: process.env.GITHUB_ACTIONS
-      ? 'https://x-govuk.github.io/govuk-eleventy-plugin/'
-      : '/',
+    url:
+      process.env.GITHUB_ACTIONS &&
+      'https://x-govuk.github.io/govuk-eleventy-plugin/',
     header: {
       logotype: 'x-govuk',
       productName: 'Eleventy Plugin',
@@ -82,6 +82,6 @@ module.exports = function (eleventyConfig) {
       input: 'docs',
       layouts: '../layouts'
     },
-    pathPrefix: process.env.GITHUB_ACTIONS ? '/govuk-eleventy-plugin/' : '/'
+    pathPrefix: process.env.GITHUB_ACTIONS && '/govuk-eleventy-plugin/'
   }
 }

index.js

@@ -26,6 +26,10 @@ module.exports = function (eleventyConfig, pluginOptions = {}) {
   eleventyConfig.addTemplateFormats('scss')
 
   // Filters
+  eleventyConfig.addFilter(
+    'canonicalUrl',
+    require('./lib/filters/canonical-url.js')
+  )
   eleventyConfig.addFilter('date', require('./lib/filters/date.js'))
   eleventyConfig.addFilter('includes', require('./lib/filters/includes.js'))
   eleventyConfig.addFilter(

layouts/base.njk

@@ -1,6 +1,6 @@
 {% extends "govuk/template.njk" %}
 
-{% set assetUrl = assetPath | absoluteUrl(options.url) %}
+{% set assetUrl = assetPath | canonicalUrl %}
 {% set themeColor = options.themeColour %}
 
 {# Only show default Open Graph image if document does not provide its own #}
@@ -41,15 +41,15 @@
 {% block head %}
   <link rel="stylesheet" href="/assets/govuk.css">
   {% for stylesheet in options.stylesheets %}
-  <link rel="stylesheet" href="{{ stylesheet | absoluteUrl(options.url) }}">
+  <link rel="stylesheet" href="{{ stylesheet | canonicalUrl }}">
   {% endfor %}
 
-  <meta property="og:url" content="{{ page.url | absoluteUrl(options.url) }}">
+  {% if options.url %}<meta property="og:url" content="{{ page.url | canonicalUrl }}">{% endif %}
   <meta property="og:title" content="{{ title }}">
   {% if description %}<meta property="og:description" name="description" content="{{ description | markdown("inline") | striptags(true) }}">{% endif %}
   {% if opengraphImage %}<meta name="twitter:card" content="summary_large_image">{% endif %}
-  {% if opengraphImage.src %}<meta name="twitter:image" content="{{ opengraphImage.src | absoluteUrl(options.url) }}">
-  <meta property="og:image" content="{{ opengraphImage.src | absoluteUrl(options.url) }}">{% endif %}
+  {% if opengraphImage.src %}<meta name="twitter:image" content="{{ opengraphImage.src | canonicalUrl }}">
+  <meta property="og:image" content="{{ opengraphImage.src | canonicalUrl }}">{% endif %}
   {% if opengraphImage.alt %}<meta property="og:image:alt" content="{{ opengraphImage.alt }}">{% endif %}
 {% endblock %}
 

lib/filters/canonical-url.js

@@ -0,0 +1,31 @@
+const path = require('node:path')
+
+/**
+ * Get canonical site URL with resolved path
+ * @param {string} string - Path to resolve
+ * @returns {string} Canonical site URL with resolved path
+ */
+module.exports = function (string) {
+  const { url } = this.ctx.options
+
+  // If plugin options do not provide a site URL, return the path
+  if (!URL.canParse(url)) {
+    return string
+  }
+
+  const siteUrl = new URL(url)
+
+  // If incoming string is a URL, return that if it’s an external URL
+  if (URL.canParse(string)) {
+    const incomingUrl = new URL(string)
+
+    if (siteUrl.hostname !== incomingUrl.hostname) {
+      return string
+    }
+  }
+
+  // String is a path, so append it to any path on site URL
+  siteUrl.pathname = path.join(siteUrl.pathname, string)
+
+  return siteUrl.href
+}

package.json

@@ -50,7 +50,6 @@
   "dependencies": {
     "@11ty/eleventy": "^2.0.0",
     "@11ty/eleventy-navigation": "^0.3.2",
-    "@11ty/eleventy-plugin-rss": "^1.1.2",
     "@rollup/plugin-commonjs": "^25.0.0",
     "@rollup/plugin-node-resolve": "^15.0.0",
     "@x-govuk/govuk-prototype-components": "^2.2.0",
@@ -89,6 +88,6 @@
     "stylelint-config-gds": "^1.0.0"
   },
   "engines": {
-    "node": ">=18"
+    "node": ">=18.17"
   }
 }

test/lib/filters/canonical-url.js

@@ -0,0 +1,13 @@
+const assert = require('assert/strict')
+const { describe, it } = require('node:test')
+const canonicalURL = require('../../../lib/filters/canonical-url.js')
+
+// TODO: Work out how to pass Nunjucks `this` context to filter for testing
+describe('canonicalURL filter', () => {
+  // it('Returns path if no site options', () => {
+  // })
+  // it('Returns URL if hostname does not match that of site', () => {
+  // })
+  // it('Returns URL with path added', () => {
+  // })
+})