* Add action truncate()

Author: Matej Szendi

README.md

@@ -120,6 +120,7 @@ const UsernameSchema = tb.pipe(tb.string(), tb.trim());
 |                                                    | `trim()` - Removes whitespace from both ends                                                              |                                                          |
 |                                                    | `trimEnd()` - Removes whitespace from the end                                                             |                                                          |
 |                                                    | `trimStart()` - Removes whitespace from the start                                                         |                                                          |
+|                                                    | `truncate()` - Shortens a string to a specified maximum length with an optional suffix                    |                                                          |
 
 These actions can be chained and combined as needed using `pipe()` function to create complex transformation schemas for converting and processing input data.
 

src/actions/truncate.ts

@@ -0,0 +1,17 @@
+import type { Action } from "../types.ts";
+
+export type TruncateAction = Action<string | null, string | null>;
+
+export function truncate(maxLength: number, suffix = "..."): TruncateAction {
+  return (input) => {
+    if (input === null) {
+      return null;
+    }
+
+    if (input.length <= maxLength) {
+      return input;
+    }
+
+    return input.substring(0, maxLength) + suffix;
+  };
+}