feat(filters): move permalink function into file, add test

# Conflicts:
#	.eleventy.js

.eleventy.js

@@ -1,15 +1,15 @@
-const makeItemLink = (slug) => `#${slug}`;
 const findExistingDefinition = require('./11ty/filters/helpers/findExistingDefinition');
+const definitionPermalink = require('./11ty/filters/definitionPermalink');
 
 module.exports = function(config) {
   // Add a filter using the Config API
-  config.addFilter('linkTarget', makeItemLink);
+  config.addFilter('linkTarget', definitionPermalink);
 
   config.addFilter('linkIfExistsInCollection', (word, collection) => {
     const existingDefinition = findExistingDefinition(word, collection);
 
     if (existingDefinition) {
-      return `<a href="${makeItemLink(
+      return `<a href="${definitionPermalink(
         existingDefinition.data.slug
       )}">${word}</a>`;
     }
@@ -24,7 +24,7 @@ module.exports = function(config) {
     );
 
     if (existingDefinition) {
-      return `<a href="${makeItemLink(
+      return `<a href="${definitionPermalink(
         existingDefinition.data.slug
       )}" aria-label="${subTermData.full_title}">${subTermData.text}</a>`;
     }

11ty/filters/_tests/definitionPermalink.spec.js

@@ -0,0 +1,7 @@
+import test from 'ava';
+
+import definitionPermalink from '../definitionPermalink';
+
+test('constructs correct detail link', (t) => {
+  t.is(definitionPermalink('test-slug'), '/definitions/test-slug/');
+});

11ty/filters/definitionPermalink.js

@@ -0,0 +1,3 @@
+module.exports = function(slug) {
+  return `/definitions/${slug}/`;
+};