fix: tolerate trailing semicolons in browser evaluate

When tsx/esbuild compiles arrow functions, it adds a __name helper
for debugging. This helper doesn't exist in the browser context,
causing 'ReferenceError: __name is not defined' when using
page.evaluate() with inline functions.

The fix uses new Function() constructed at runtime, which esbuild
doesn't transform, avoiding the __name injection.

CHANGELOG.md

@@ -18,6 +18,7 @@
 - Discord: emit system events for reaction add/remove with per-guild reaction notifications (off|own|all|allowlist) (#140) — thanks @thewilloftheshadow.
 
 ### Fixes
+- Browser tools: tolerate trailing semicolons in evaluate expressions (#153) — thanks @azade-c.
 - Auto-reply: drop final payloads when block streaming to avoid duplicate Discord sends.
 - Bash tool: default auto-background delay to 10s.
 - Telegram: chunk block-stream replies to avoid “message is too long” errors (#124) — thanks @mukhtharcm.

src/browser/pw-tools-core.test.ts

@@ -232,4 +232,41 @@ describe("pw-tools-core", () => {
     expect(dismiss).toHaveBeenCalled();
     expect(accept).not.toHaveBeenCalled();
   });
+
+  it("evaluates expressions with trailing semicolons", async () => {
+    const evaluate = vi.fn(
+      async (fn: (body: string) => unknown, body: string) => fn(body),
+    );
+    currentPage = { evaluate };
+
+    const mod = await importModule();
+    const result = await mod.evaluateViaPlaywright({
+      cdpUrl: "http://127.0.0.1:18792",
+      fn: "() => 42;",
+    });
+
+    expect(result).toBe(42);
+    expect(evaluate).toHaveBeenCalled();
+  });
+
+  it("evaluates element expressions with trailing semicolons", async () => {
+    const evaluate = vi.fn(
+      async (
+        fn: (el: { tagName: string }, body: string) => unknown,
+        body: string,
+      ) => fn({ tagName: "DIV" }, body),
+    );
+    currentRefLocator = { evaluate };
+    currentPage = {};
+
+    const mod = await importModule();
+    const result = await mod.evaluateViaPlaywright({
+      cdpUrl: "http://127.0.0.1:18792",
+      fn: "(el) => el.tagName;",
+      ref: "1",
+    });
+
+    expect(result).toBe("DIV");
+    expect(sessionMocks.refLocator).toHaveBeenCalledWith(currentPage, "1");
+  });
 });

src/browser/pw-tools-core.ts

@@ -207,53 +207,44 @@ export async function evaluateViaPlaywright(opts: {
 }): Promise<unknown> {
   const fnText = String(opts.fn ?? "").trim();
   if (!fnText) throw new Error("function is required");
+  const fnBody = fnText.replace(/[;\s]+$/g, "");
+  if (!fnBody) throw new Error("function is required");
   const page = await getPageForTargetId(opts);
   ensurePageState(page);
   if (opts.ref) {
     const locator = refLocator(page, opts.ref);
-    return await locator.evaluate((el, fnBody) => {
+    // Use Function constructor at runtime to avoid esbuild adding __name helper
-      const compileRunner = (body: string) => {
+    // which doesn't exist in the browser context
-        const inner = `"use strict"; const candidate = ${body}; return typeof candidate === "function" ? candidate(element) : candidate;`;
+    const elementEvaluator = new Function(
-        // This intentionally evaluates user-supplied code in the browser context.
+      "el",
-        // oxlint-disable-next-line typescript-eslint/no-implied-eval
+      "fnBody",
-        return new Function("element", inner) as (element: Element) => unknown;
+      `
-      };
+      "use strict";
-      let compiled: unknown;
       try {
-        compiled = compileRunner(fnBody);
+        var candidate = eval("(" + fnBody + ")");
+        return typeof candidate === "function" ? candidate(el) : candidate;
       } catch (err) {
-        const message =
+        throw new Error("Invalid evaluate function: " + (err && err.message ? err.message : String(err)));
-          err instanceof Error
-            ? err.message
-            : typeof err === "string"
-              ? err
-              : "invalid expression";
-        throw new Error(`Invalid evaluate function: ${message}`);
       }
-      return (compiled as (element: Element) => unknown)(el as Element);
+      `,
-    }, fnText);
+    ) as (el: Element, fnBody: string) => unknown;
+    return await locator.evaluate(elementEvaluator, fnBody);
   }
-  return await page.evaluate((fnBody) => {
+  // Use Function constructor at runtime to avoid esbuild adding __name helper
-    const compileRunner = (body: string) => {
+  // which doesn't exist in the browser context
-      const inner = `"use strict"; const candidate = ${body}; return typeof candidate === "function" ? candidate() : candidate;`;
+  const browserEvaluator = new Function(
-      // This intentionally evaluates user-supplied code in the browser context.
+    "fnBody",
-      // oxlint-disable-next-line typescript-eslint/no-implied-eval
+    `
-      return new Function(inner) as () => unknown;
+    "use strict";
-    };
-    let compiled: unknown;
     try {
-      compiled = compileRunner(fnBody);
+      var candidate = eval("(" + fnBody + ")");
+      return typeof candidate === "function" ? candidate() : candidate;
     } catch (err) {
-      const message =
+      throw new Error("Invalid evaluate function: " + (err && err.message ? err.message : String(err)));
-        err instanceof Error
-          ? err.message
-          : typeof err === "string"
-            ? err
-            : "invalid expression";
-      throw new Error(`Invalid evaluate function: ${message}`);
     }
-    return (compiled as () => unknown)();
+    `,
-  }, fnText);
+  ) as (fnBody: string) => unknown;
+  return await page.evaluate(browserEvaluator, fnBody);
 }
 
 export async function armFileUploadViaPlaywright(opts: {