Revert "Revert "fix(banned words): fix partial matching of words containing diacritic… (#12444)""

This reverts commit 5362058f35.

website/server/libs/stringUtils.js

@@ -4,12 +4,21 @@ export function removePunctuationFromString (str) {
 
 // NOTE: the wordsToMatch aren't escaped in order to support regular expressions,
 // so this method should not be used if wordsToMatch contains unsanitized user input
+
 export function getMatchesByWordArray (str, wordsToMatch) {
+  // remove accented characters from the string, which would trip up the regEx
+  // later on, by using the built-in Unicode normalisation methods
+  // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/normalize
+  // https://www.unicode.org/reports/tr15/#Canon_Compat_Equivalence
+  // https://unicode-table.com/en/#combining-diacritical-marks
+
+  const normalizedStr = str.normalize('NFD').replace(/[\u0300-\u036f]/g, '');
+
   const matchedWords = [];
   const wordRegexs = wordsToMatch.map(word => new RegExp(`\\b([^a-z]+)?${word}([^a-z]+)?\\b`, 'i'));
   for (let i = 0; i < wordRegexs.length; i += 1) {
     const regEx = wordRegexs[i];
-    const match = str.match(regEx);
+    const match = normalizedStr.match(regEx);
     if (match !== null && match[0] !== null) {
       const trimmedMatch = removePunctuationFromString(match[0]).trim();
       matchedWords.push(trimmedMatch);