From b7b2b0d4348a758e5f37c226bd26edf0d667fba8 Mon Sep 17 00:00:00 2001
From: fisker Cheung <lionkay@gmail.com>
Date: Tue, 23 Sep 2025 17:51:36 +0800
Subject: [PATCH] Print trailing comma in `TSImportType` options (#17798)

---
 changelog_unreleased/typescript/17798.md      | 27 ++++++++++++++
 src/language-js/print/object.js               |  7 +---
 .../comma/__snapshots__/format.test.js.snap   | 37 +++++++++++++++++++
 .../typescript/import-type/comma/comma.ts     | 10 +++++
 .../import-type/comma/format.test.js          |  1 +
 .../__snapshots__/format.test.js.snap         |  4 +-
 6 files changed, 78 insertions(+), 8 deletions(-)
 create mode 100644 changelog_unreleased/typescript/17798.md
 create mode 100644 tests/format/typescript/import-type/comma/__snapshots__/format.test.js.snap
 create mode 100644 tests/format/typescript/import-type/comma/comma.ts
 create mode 100644 tests/format/typescript/import-type/comma/format.test.js

diff --git a/changelog_unreleased/typescript/17798.md b/changelog_unreleased/typescript/17798.md
new file mode 100644
index 000000000..d1aff05f6
--- /dev/null
+++ b/changelog_unreleased/typescript/17798.md
@@ -0,0 +1,27 @@
+#### Print trailing comma in `TSImportType` options (#17798 by @fisker)
+
+Trailing comma in import type attribute wasn't allowed before TypeScript v5.9, now [the bug](https://github.com/microsoft/TypeScript/issues/61916) has been fixed.
+
+<!-- prettier-ignore -->
+```tsx
+// Input
+type A = import("foo", {
+    with:{
+        type:'json',
+    }  // <- Should be a comma here
+})
+
+// Prettier stable
+type A = import("foo", {
+  with: {
+    type: "json",
+  } // <- Should be a comma here
+});
+
+// Prettier main
+type A = import("foo", {
+  with: {
+    type: "json",
+  }, // <- Should be a comma here
+});
+```
diff --git a/src/language-js/print/object.js b/src/language-js/print/object.js
index e04b2ee20..32fcd58a8 100644
--- a/src/language-js/print/object.js
+++ b/src/language-js/print/object.js
@@ -161,12 +161,7 @@ function printObject(path, options, print) {
           lastElem.type === "TSMethodSignature" ||
           lastElem.type === "TSConstructSignatureDeclaration" ||
           lastElem.type === "TSIndexSignature") &&
-          hasComment(lastElem, CommentCheckFlags.PrettierIgnore)))) ||
-    // https://github.com/microsoft/TypeScript/issues/61916
-    path.match(
-      undefined,
-      (node, key) => node.type === "TSImportType" && key === "options",
-    )
+          hasComment(lastElem, CommentCheckFlags.PrettierIgnore))))
   );
 
   let content;
diff --git a/tests/format/typescript/import-type/comma/__snapshots__/format.test.js.snap b/tests/format/typescript/import-type/comma/__snapshots__/format.test.js.snap
new file mode 100644
index 000000000..7a50b1102
--- /dev/null
+++ b/tests/format/typescript/import-type/comma/__snapshots__/format.test.js.snap
@@ -0,0 +1,37 @@
+// Jest Snapshot v1, https://jestjs.io/docs/snapshot-testing
+
+exports[`comma.ts format 1`] = `
+====================================options=====================================
+parsers: ["typescript"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+type A = import("foo", {
+  with: {
+  type: "json",}})
+type A = import("foo", {
+  with: {
+  type: "json"},})
+// Not supported, https://github.com/microsoft/TypeScript/issues/61489
+// type A = import("foo", {
+//   with: {
+//   type: "json"}},)
+
+=====================================output=====================================
+type A = import("foo", {
+  with: {
+    type: "json",
+  },
+});
+type A = import("foo", {
+  with: {
+    type: "json",
+  },
+});
+// Not supported, https://github.com/microsoft/TypeScript/issues/61489
+// type A = import("foo", {
+//   with: {
+//   type: "json"}},)
+
+================================================================================
+`;
diff --git a/tests/format/typescript/import-type/comma/comma.ts b/tests/format/typescript/import-type/comma/comma.ts
new file mode 100644
index 000000000..3c90a1324
--- /dev/null
+++ b/tests/format/typescript/import-type/comma/comma.ts
@@ -0,0 +1,10 @@
+type A = import("foo", {
+  with: {
+  type: "json",}})
+type A = import("foo", {
+  with: {
+  type: "json"},})
+// Not supported, https://github.com/microsoft/TypeScript/issues/61489
+// type A = import("foo", {
+//   with: {
+//   type: "json"}},)
diff --git a/tests/format/typescript/import-type/comma/format.test.js b/tests/format/typescript/import-type/comma/format.test.js
new file mode 100644
index 000000000..116dcbd78
--- /dev/null
+++ b/tests/format/typescript/import-type/comma/format.test.js
@@ -0,0 +1 @@
+runFormatTest(import.meta, ["typescript"]);
diff --git a/tests/format/typescript/import-type/long-module-name/__snapshots__/format.test.js.snap b/tests/format/typescript/import-type/long-module-name/__snapshots__/format.test.js.snap
index 20d11c7d3..e9d610445 100644
--- a/tests/format/typescript/import-type/long-module-name/__snapshots__/format.test.js.snap
+++ b/tests/format/typescript/import-type/long-module-name/__snapshots__/format.test.js.snap
@@ -147,13 +147,13 @@ type C = import(
   {
     with: {
       type: "json",
-    }
+    },
   }
 );
 type D = import(
   "./long/long/long/long/long/long/long/long/long/long/path/to/module",
   {
-    with: { type: "json" }
+    with: { type: "json" },
   }
 );