MDL-82754 core: Improve treatStringsInContent() performance with arrays

Co-authored-by: JeanSotoriva <[email protected]>

lib/amd/src/local/templates/renderer.js

@@ -477,7 +477,7 @@ export default class Renderer {
         // Placeholders are in the for [[_sX]] or [[_cX]] where X is the string index.
         const stringPattern = /(?<placeholder>\[\[_(?<stringType>[cs])(?<stringIndex>\d+)\]\])/g;
 
-        // A helpre to fetch the string for a given placeholder.
+        // A helper to fetch the string for a given placeholder.
         const getUpdatedString = ({placeholder, stringType, stringIndex}) => {
             if (stringMap.has(placeholder)) {
                 return stringMap.get(placeholder);
@@ -493,20 +493,41 @@ export default class Renderer {
             }
 
             Log.debug(`Could not find string for pattern ${placeholder}`);
-            return '';
+            return ''; // Fallback if no match is found.
         };
 
-        // Find all placeholders in the content and replace them with their respective strings.
-        let match;
-        while ((match = stringPattern.exec(content)) !== null) {
-            let updatedContent = content.slice(0, match.index);
-            updatedContent += getUpdatedString(match.groups);
-            updatedContent += content.slice(match.index + match.groups.placeholder.length);
+        let updatedContent = content; // Start with the original content.
+        let placeholderFound = true; // Flag to track if we are still finding placeholders.
 
-            content = updatedContent;
+        // Continue looping until no more placeholders are found in the updated content.
+        while (placeholderFound) {
+            let match;
+            let result = [];
+            let lastIndex = 0;
+            placeholderFound = false; // Assume no placeholders are found.
+
+            // Find all placeholders in the content and replace them with their respective strings.
+            while ((match = stringPattern.exec(updatedContent)) !== null) {
+                placeholderFound = true; // A placeholder was found, so continue looping.
+
+                // Add the content before the matched placeholder.
+                result.push(updatedContent.slice(lastIndex, match.index));
+
+                // Add the updated string for the placeholder.
+                result.push(getUpdatedString(match.groups));
+
+                // Update lastIndex to move past the current match.
+                lastIndex = match.index + match[0].length;
+            }
+
+            // Add the remaining part of the content after the last match.
+            result.push(updatedContent.slice(lastIndex));
+
+            // Join the parts of the result array into the updated content.
+            updatedContent = result.join('');
         }
 
-        return content;
+        return updatedContent; // Return the fully updated content after all loops.
     }
 
     /**