Creates a handlebars instance per invocation of load Templates.

lib/templates.js

@@ -4,47 +4,6 @@ import handlebars from 'handlebars';
 
 const dateFormatter = new Intl.DateTimeFormat('en-GB', { dateStyle: 'full', timeZone: 'UTC' });
 
-// A helper to turn a datetime into a human readable string.
-handlebars.registerHelper('humanDate', stamp => dateFormatter.format(new Date(stamp)));
-handlebars.registerHelper('humanDateTime', (stamp, timeZone) => {
-  return new Intl.DateTimeFormat('en-GB', { dateStyle: 'full', timeStyle: 'long', timeZone }).format(new Date(stamp));
-});
-handlebars.registerHelper('navElement', function (url, name) {
-  const escapedName = handlebars.escapeExpression(name);
-
-  if (url === this.localUrl) { // eslint-disable-line no-invalid-this
-    return escapedName;
-  }
-
-  const escapedUrl = handlebars.escapeExpression(url);
-
-  return new handlebars.SafeString(`<a href="${escapedUrl}">${escapedName}</a>`);
-});
-handlebars.registerHelper('encodeUriComponent', encodeURIComponent);
-
-// A helper to turn a datetime into an ISO string (without milliseconds).
-handlebars.registerHelper('isoDate', datetime => new Date(datetime)
-  .toISOString()
-  .replace(/\.\d{3}Z/, 'Z')
-);
-
-handlebars.registerHelper('initialUpper', string => string[0].toUpperCase() + string.slice(1));
-
-const year = new Date().getUTCFullYear();
-
-handlebars.registerHelper('year', () => year);
-
-handlebars.registerHelper('hash', (field, chars) => {
-  return createHash('sha256')
-    .update(field)
-    .digest('hex')
-    .slice(0, chars);
-});
-
-handlebars.registerHelper('ifeq', function (a, b, { fn, inverse }) {
-  return a === b ? fn(this) : inverse(this); // eslint-disable-line no-invalid-this
-});
-
 function makePicker(list) {
   let filtered = list;
 
@@ -58,18 +17,62 @@ function makePicker(list) {
   };
 }
 
-handlebars.registerHelper('lightEmoji', makePicker(['🌴', '☀️', '🕶', '🐬', '🦜', '🍉']));
-handlebars.registerHelper('darkEmoji', makePicker(['⭐️', '🌙', '🍹', '🌴', '🎷']));
-
 async function getTemplateAndName(directory, filename) {
   const source = await readFile(new URL(filename, directory), 'utf8');
   const name = filename.slice(0, filename.lastIndexOf('.', filename.length - 12)); // trim off .ext.handlebars
 
   return [name, source.trim()];
 }
 
-export default async function loadTemplates(dir, { baseTitle }) {
-  handlebars.registerHelper('baseTitle', () => baseTitle);
+export default async function loadTemplates(dir, { baseTitle: title }) {
+  const fullYear = new Date().getUTCFullYear();
+  const bars = handlebars.create();
+
+  bars.registerHelper({
+    baseTitle() {
+      return title;
+    },
+    lightEmoji: makePicker(['🌴', '☀️', '🕶', '🐬', '🦜', '🍉']),
+    darkEmoji: makePicker(['⭐️', '🌙', '🍹', '🌴', '🎷']),
+    ifeq(a, b, { fn, inverse }) {
+      return a === b ? fn(this) : inverse(this); // eslint-disable-line no-invalid-this
+    },
+    hash(field, chars) {
+      return createHash('sha256')
+        .update(field)
+        .digest('hex')
+        .slice(0, chars);
+    },
+    year() {
+      return fullYear;
+    },
+    initialUpper(string) {
+      return string[0].toUpperCase() + string.slice(1);
+    },
+    isoDate(datetime) {
+      return new Date(datetime)
+        .toISOString()
+        .replace(/\.\d{3}Z/, 'Z');
+    },
+    encodeUriComponent: encodeURIComponent,
+    navElement(url, name) {
+      const escapedName = bars.escapeExpression(name);
+
+      if (url === this.localUrl) { // eslint-disable-line no-invalid-this
+        return escapedName;
+      }
+
+      const escapedUrl = bars.escapeExpression(url);
+
+      return new bars.SafeString(`<a href="${escapedUrl}">${escapedName}</a>`);
+    },
+    humanDateTime(stamp, timeZone) {
+      return new Intl.DateTimeFormat('en-GB', { dateStyle: 'full', timeStyle: 'long', timeZone }).format(new Date(stamp));
+    },
+    humanDate(stamp) {
+      return dateFormatter.format(new Date(stamp));
+    }
+  });
 
   const partialsPath = new URL('partials/', dir);
   const templatesPath = new URL('documents/', dir);
@@ -89,13 +92,13 @@ export default async function loadTemplates(dir, { baseTitle }) {
         return Promise.all(partialFilenames.map(async n => {
           const [name, source] = await getTemplateAndName(partialsPath, n);
 
-          handlebars.registerPartial(name, source);
+          bars.registerPartial(name, source);
         }));
       })
   ]);
 
   for (const [name, source] of documentsSources) {
-    templates[name] = handlebars.compile(source);
+    templates[name] = bars.compile(source);
   }
 
   return templates;