From c9c9f859f3f9118e707ff3cef6a2a02e2d599890 Mon Sep 17 00:00:00 2001
From: xiaofa <xiaofalzx@gmail.com>
Date: Thu, 17 Jan 2019 05:51:57 +0800
Subject: [PATCH] fix quick fix infer parameter types from usage in js file

---
 src/services/textChanges.ts                    |  4 +++-
 .../fourslash/codeFixInferFromUsageArrowJS.ts  | 18 ++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 tests/cases/fourslash/codeFixInferFromUsageArrowJS.ts

diff --git a/src/services/textChanges.ts b/src/services/textChanges.ts
index 4689e18508c..7dab7205841 100644
--- a/src/services/textChanges.ts
+++ b/src/services/textChanges.ts
@@ -340,7 +340,9 @@ namespace ts.textChanges {
         }
 
         public insertJsdocCommentBefore(sourceFile: SourceFile, node: HasJSDoc, tag: JSDoc): void {
-            const fnStart = node.getStart(sourceFile);
+            const fnStart = node.kind === SyntaxKind.ArrowFunction
+                ? node.parent.parent.getStart(sourceFile)
+                : node.getStart(sourceFile);
             if (node.jsDoc) {
                 for (const jsdoc of node.jsDoc) {
                     this.deleteRange(sourceFile, {
diff --git a/tests/cases/fourslash/codeFixInferFromUsageArrowJS.ts b/tests/cases/fourslash/codeFixInferFromUsageArrowJS.ts
new file mode 100644
index 00000000000..e867ae99c75
--- /dev/null
+++ b/tests/cases/fourslash/codeFixInferFromUsageArrowJS.ts
@@ -0,0 +1,18 @@
+/// <reference path='fourslash.ts' />
+// @allowJs: true
+// @checkJs: true
+// @noEmit: true
+// @noImplicitAny: true
+// @Filename: test.js
+
+////const foo = x => x.y + 1;
+
+verify.codeFix({
+  description: "Infer parameter types from usage",
+  index: 0,
+  newFileContent:
+`/**
+ * @param {{ y: number; }} x
+ */
+const foo = x => x.y + 1;`,
+});
\ No newline at end of file