diff --git a/src/lib/esnext.string.d.ts b/src/lib/esnext.string.d.ts
index c13d3e48a37..66971bf84d6 100644
--- a/src/lib/esnext.string.d.ts
+++ b/src/lib/esnext.string.d.ts
@@ -5,4 +5,11 @@ interface String {
      * @param replaceValue A string containing the text to replace for every successful match of searchValue in this string.
      */
     replaceAll(searchValue: string | RegExp, replaceValue: string): string;
+
+    /**
+     * Replace all instances of a substring in a string, using a regular expression or search string.
+     * @param searchValue A string to search for.
+     * @param replacer A function that returns the replacement text.
+     */
+    replaceAll(searchValue: string | RegExp, replacer: (substring: string, ...args: any[]) => string): string;
 }