Show notifications when a user's profile name changes

js/modules/i18n.js

@@ -1,5 +1,7 @@
-/* eslint-env node */
-/* global log */
+/* eslint-env node, browser */
+
+// eslint-disable-next-line no-console
+const log = typeof window !== 'undefined' ? window.log : console;
 
 exports.setup = (locale, messages) => {
   if (!locale) {
@@ -17,18 +19,57 @@ exports.setup = (locale, messages) => {
       );
       return '';
     }
+    if (Array.isArray(substitutions) && substitutions.length > 1) {
+      throw new Error(
+        'Array syntax is not supported with more than one placeholder'
+      );
+    }
+    if (
+      typeof substitutions === 'string' ||
+      typeof substitutions === 'number'
+    ) {
+      throw new Error('You must provide either a map or an array');
+    }
 
     const { message } = entry;
-    if (Array.isArray(substitutions)) {
+    if (!substitutions) {
+      return message;
+    } else if (Array.isArray(substitutions)) {
       return substitutions.reduce(
         (result, substitution) => result.replace(/\$.+?\$/, substitution),
         message
       );
-    } else if (substitutions) {
-      return message.replace(/\$.+?\$/, substitutions);
     }
 
-    return message;
+    const FIND_REPLACEMENTS = /\$([^$]+)\$/g;
+
+    let match = FIND_REPLACEMENTS.exec(message);
+    let builder = '';
+    let lastTextIndex = 0;
+
+    while (match) {
+      if (lastTextIndex < match.index) {
+        builder += message.slice(lastTextIndex, match.index);
+      }
+
+      const placeholderName = match[1];
+      const value = substitutions[placeholderName];
+      if (!value) {
+        log.error(
+          `i18n: Value not provided for placeholder ${placeholderName} in key '${key}'`
+        );
+      }
+      builder += value || '';
+
+      lastTextIndex = FIND_REPLACEMENTS.lastIndex;
+      match = FIND_REPLACEMENTS.exec(message);
+    }
+
+    if (lastTextIndex < message.length) {
+      builder += message.slice(lastTextIndex);
+    }
+
+    return builder;
   }
 
   getMessage.getLocale = () => locale;