fix(truncate): guard update() options in truncate action

Author: metonym

src/Truncate/truncate.d.ts

@@ -2,6 +2,12 @@ interface TruncateOptions {
   clamp?: "end" | "front";
 }
 
+/**
+ * Svelte action that applies single-line text truncation to an element.
+ * @param node - The element to truncate
+ * @param options - Optional clamp direction ("end" or "front")
+ * @returns Object with update method (options may be undefined when action is updated with no args)
+ */
 export function truncate(
   node: HTMLElement,
   options?: TruncateOptions,

src/Truncate/truncate.js

@@ -21,7 +21,7 @@ export function truncate(node, options = {}) {
 
   return {
     update(options) {
-      toggleClass(options.clamp === "front");
+      toggleClass(options?.clamp === "front");
     },
   };
 }

tests/Truncate/Truncate.test.ts

@@ -1,4 +1,5 @@
 import { render, screen } from "@testing-library/svelte";
+import { truncate } from "../../src/Truncate/truncate.js";
 import Truncate from "./Truncate.test.svelte";
 import TruncateAction from "./TruncateAction.test.svelte";
 
@@ -86,5 +87,12 @@ describe("Truncate", () => {
       const element = screen.getByText(/This is a long text/);
       expect(element).toHaveClass("bx--text-truncate--end");
     });
+
+    it("update() with no arguments does not throw (options optional guard)", () => {
+      const node = document.createElement("p");
+      const { update } = truncate(node);
+      expect(() => update()).not.toThrow();
+      expect(() => update(undefined)).not.toThrow();
+    });
   });
 });