From 689efe3cd26a664a85afefbcfaa098d3bbab7984 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Mon, 23 Sep 2024 10:09:50 -0700
Subject: [PATCH 1/9] Add rewriteRelativeImportExtension helper

---
 modules/index.d.ts                            |  1 +
 modules/index.js                              |  2 +
 .../rewriteRelativeImportExtension.test.js    | 49 +++++++++++++++++++
 tslib.d.ts                                    |  7 +++
 tslib.es6.js                                  | 18 +++++++
 tslib.es6.mjs                                 | 18 +++++++
 tslib.js                                      | 20 ++++++++
 7 files changed, 115 insertions(+)
 create mode 100644 test/node/rewriteRelativeImportExtension.test.js

diff --git a/modules/index.d.ts b/modules/index.d.ts
index 0fedae8..3244fab 100644
--- a/modules/index.d.ts
+++ b/modules/index.d.ts
@@ -33,5 +33,6 @@ export {
   __createBinding,
   __addDisposableResource,
   __disposeResources,
+  __rewriteRelativeImportExtension,
 } from '../tslib.js';
 export * as default from '../tslib.js';
diff --git a/modules/index.js b/modules/index.js
index af9f5ac..c91f618 100644
--- a/modules/index.js
+++ b/modules/index.js
@@ -31,6 +31,7 @@ const {
     __classPrivateFieldIn,
     __addDisposableResource,
     __disposeResources,
+    __rewriteRelativeImportExtension,
 } = tslib;
 export {
     __extends,
@@ -64,5 +65,6 @@ export {
     __classPrivateFieldIn,
     __addDisposableResource,
     __disposeResources,
+    __rewriteRelativeImportExtension,
 };
 export default tslib;
diff --git a/test/node/rewriteRelativeImportExtension.test.js b/test/node/rewriteRelativeImportExtension.test.js
new file mode 100644
index 0000000..772d173
--- /dev/null
+++ b/test/node/rewriteRelativeImportExtension.test.js
@@ -0,0 +1,49 @@
+import assert from "node:assert";
+import { test } from "node:test";
+import { testHelper } from "./testHelper.js";
+
+testHelper("__rewriteRelativeImportExtension", __rewriteRelativeImportExtension => {
+  test("rewrites relative .ts to .js", () => {
+    assert.equal(__rewriteRelativeImportExtension("./foo.ts"), "./foo.js");
+    assert.equal(__rewriteRelativeImportExtension("../foo.ts"), "../foo.js");
+    assert.equal(__rewriteRelativeImportExtension("../../foo.ts"), "../../foo.js");
+  });
+
+  test("rewrites other TypeScript extensions", () => {
+    assert.equal(__rewriteRelativeImportExtension("./foo.mts"), "./foo.mjs");
+    assert.equal(__rewriteRelativeImportExtension("./foo.cts"), "./foo.cjs");
+    assert.equal(__rewriteRelativeImportExtension("./foo.tsx"), "./foo.js");
+    assert.equal(__rewriteRelativeImportExtension("./foo.tsx", true), "./foo.jsx");
+  });
+
+  test("does not rewrite other extensions", () => {
+    assert.equal(__rewriteRelativeImportExtension("./foo.js"), "./foo.js");
+    assert.equal(__rewriteRelativeImportExtension("./foo.mjs"), "./foo.mjs");
+    assert.equal(__rewriteRelativeImportExtension("./foo.cjs"), "./foo.cjs");
+    assert.equal(__rewriteRelativeImportExtension("./foo.jsx"), "./foo.jsx");
+    assert.equal(__rewriteRelativeImportExtension("./foo.json"), "./foo.json");
+    assert.equal(__rewriteRelativeImportExtension("./foo.css"), "./foo.css");
+    assert.equal(__rewriteRelativeImportExtension("./foo"), "./foo");
+  });
+
+  test("does not rewrite non-relative imports", () => {
+    assert.equal(__rewriteRelativeImportExtension("foo.ts"), "foo.ts");
+    assert.equal(__rewriteRelativeImportExtension("foo.mts"), "foo.mts");
+    assert.equal(__rewriteRelativeImportExtension("foo.cts"), "foo.cts");
+    assert.equal(__rewriteRelativeImportExtension("foo.tsx"), "foo.tsx");
+    assert.equal(__rewriteRelativeImportExtension("foo.js"), "foo.js");
+    assert.equal(__rewriteRelativeImportExtension("foo.mjs"), "foo.mjs");
+    assert.equal(__rewriteRelativeImportExtension("foo.cjs"), "foo.cjs");
+    assert.equal(__rewriteRelativeImportExtension("foo.jsx"), "foo.jsx");
+    assert.equal(__rewriteRelativeImportExtension("foo.json"), "foo.json");
+    assert.equal(__rewriteRelativeImportExtension("foo.css"), "foo.css");
+    assert.equal(__rewriteRelativeImportExtension("foo"), "foo");
+  });
+
+  test("does not rewrite declaration file extensions", () => {
+    assert.equal(__rewriteRelativeImportExtension("./foo.d.ts"), "./foo.d.ts");
+    assert.equal(__rewriteRelativeImportExtension("./foo.d.mts"), "./foo.d.mts");
+    assert.equal(__rewriteRelativeImportExtension("./foo.d.cts"), "./foo.d.cts");
+    assert.equal(__rewriteRelativeImportExtension("./foo.d.css.ts"), "./foo.d.css.ts");
+  });
+});
diff --git a/tslib.d.ts b/tslib.d.ts
index 4576221..f23df55 100644
--- a/tslib.d.ts
+++ b/tslib.d.ts
@@ -451,3 +451,10 @@ export declare function __addDisposableResource<T>(env: { stack: { value?: unkno
  * @seealso {@link __addDisposableResource}
  */
 export declare function __disposeResources(env: { stack: { value?: unknown, dispose?: Function, async: boolean }[]; error: unknown; hasError: boolean; }): any;
+
+/**
+ * Transforms a relative import specifier ending in a non-declaration TypeScript file extension to its JavaScript file extension counterpart.
+ * @param path The import specifier.
+ * @param preserveJsx Causes '*.tsx' to transform to '*.jsx' instead of '*.js'. Should be true when `--jsx` is set to `preserve`.
+ */
+export declare function __rewriteRelativeImportExtension(path: string, preserveJsx?: boolean): string;
\ No newline at end of file
diff --git a/tslib.es6.js b/tslib.es6.js
index 9365006..a1323a6 100644
--- a/tslib.es6.js
+++ b/tslib.es6.js
@@ -348,6 +348,23 @@ export function __disposeResources(env) {
     return next();
 }
 
+export function __rewriteRelativeImportExtension(path, preserveJsx) {
+    if (typeof path === "string" && path[0] === "." && (path[1] === "/" || path[1] === "." && path[2] === "/")) {
+        if (path.substring(path.length - 4) === ".tsx") {
+            return path.substring(0, path.length - 4) + (preserveJsx ? ".jsx" : ".js");
+        }
+        if (path.substring(path.length - 3) === ".ts") {
+            var dot = path.lastIndexOf(".", path.length - 4);
+            if (dot >= 0 && (path.substring(dot - 2, dot) === ".d" || path.substring(dot, dot + 2) === ".d")) {
+                return path;
+            }
+            return path.substring(0, path.length - 3) + ".js";
+        }
+        return path.replace(/(?<!\.d)\.[cm]ts$/, function (ext) { return ext === ".mts" ? ".mjs" : ".cjs"; });
+    }
+    return path;
+}
+
 export default {
     __extends: __extends,
     __assign: __assign,
@@ -380,4 +397,5 @@ export default {
     __classPrivateFieldIn: __classPrivateFieldIn,
     __addDisposableResource: __addDisposableResource,
     __disposeResources: __disposeResources,
+    __rewriteRelativeImportExtension: __rewriteRelativeImportExtension,
 };
diff --git a/tslib.es6.mjs b/tslib.es6.mjs
index e669963..e225e43 100644
--- a/tslib.es6.mjs
+++ b/tslib.es6.mjs
@@ -347,6 +347,23 @@ export function __disposeResources(env) {
   return next();
 }
 
+export function __rewriteRelativeImportExtension(path, preserveJsx) {
+  if (typeof path === "string" && path[0] === "." && (path[1] === "/" || path[1] === "." && path[2] === "/")) {
+    if (path.substring(path.length - 4) === ".tsx") {
+      return path.substring(0, path.length - 4) + (preserveJsx ? ".jsx" : ".js");
+    }
+    if (path.substring(path.length - 3) === ".ts") {
+      var dot = path.lastIndexOf(".", path.length - 4);
+      if (dot >= 0 && (path.substring(dot - 2, dot) === ".d" || path.substring(dot, dot + 2) === ".d")) {
+        return path;
+      }
+      return path.substring(0, path.length - 3) + ".js";
+    }
+    return path.replace(/(?<!\.d)\.[cm]ts$/, function (ext) { return ext === ".mts" ? ".mjs" : ".cjs"; });
+  }
+  return path;
+}
+
 export default {
   __extends,
   __assign,
@@ -379,4 +396,5 @@ export default {
   __classPrivateFieldIn,
   __addDisposableResource,
   __disposeResources,
+  __rewriteRelativeImportExtension,
 };
diff --git a/tslib.js b/tslib.js
index e53dd2f..6587aa1 100644
--- a/tslib.js
+++ b/tslib.js
@@ -44,6 +44,7 @@ var __classPrivateFieldIn;
 var __createBinding;
 var __addDisposableResource;
 var __disposeResources;
+var __rewriteRelativeImportExtension;
 (function (factory) {
     var root = typeof global === "object" ? global : typeof self === "object" ? self : typeof this === "object" ? this : {};
     if (typeof define === "function" && define.amd) {
@@ -395,6 +396,23 @@ var __disposeResources;
         return next();
     };
 
+    __rewriteRelativeImportExtension = function (path, preserveJsx) {
+        if (typeof path === "string" && path[0] === "." && (path[1] === "/" || path[1] === "." && path[2] === "/")) {
+            if (path.substring(path.length - 4) === ".tsx") {
+                return path.substring(0, path.length - 4) + (preserveJsx ? ".jsx" : ".js");
+            }
+            if (path.substring(path.length - 3) === ".ts") {
+                var dot = path.lastIndexOf(".", path.length - 4);
+                if (dot >= 0 && (path.substring(dot - 2, dot) === ".d" || path.substring(dot, dot + 2) === ".d")) {
+                    return path;
+                }
+                return path.substring(0, path.length - 3) + ".js";
+            }
+            return path.replace(/(?<!\.d)\.[cm]ts$/, function (ext) { return ext === ".mts" ? ".mjs" : ".cjs"; });
+        }
+        return path;
+    };
+
     exporter("__extends", __extends);
     exporter("__assign", __assign);
     exporter("__rest", __rest);
@@ -426,6 +444,7 @@ var __disposeResources;
     exporter("__classPrivateFieldIn", __classPrivateFieldIn);
     exporter("__addDisposableResource", __addDisposableResource);
     exporter("__disposeResources", __disposeResources);
+    exporter("__rewriteRelativeImportExtension", __rewriteRelativeImportExtension);
 });
 
 0 && (module.exports = {
@@ -460,4 +479,5 @@ var __disposeResources;
     __classPrivateFieldIn,
     __addDisposableResource,
     __disposeResources,
+    __rewriteRelativeImportExtension,
 });

From e7b6aa0a882601b7352edfb3799c92d85006aaab Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Tue, 24 Sep 2024 09:32:46 -0700
Subject: [PATCH 2/9] Case insensitivity, remove lookbehind

---
 .../rewriteRelativeImportExtension.test.js    |  4 ++++
 tslib.es6.js                                  | 13 ++++++------
 tslib.es6.mjs                                 | 21 ++++++++++---------
 tslib.js                                      | 13 ++++++------
 4 files changed, 29 insertions(+), 22 deletions(-)

diff --git a/test/node/rewriteRelativeImportExtension.test.js b/test/node/rewriteRelativeImportExtension.test.js
index 772d173..25158e1 100644
--- a/test/node/rewriteRelativeImportExtension.test.js
+++ b/test/node/rewriteRelativeImportExtension.test.js
@@ -7,6 +7,8 @@ testHelper("__rewriteRelativeImportExtension", __rewriteRelativeImportExtension
     assert.equal(__rewriteRelativeImportExtension("./foo.ts"), "./foo.js");
     assert.equal(__rewriteRelativeImportExtension("../foo.ts"), "../foo.js");
     assert.equal(__rewriteRelativeImportExtension("../../foo.ts"), "../../foo.js");
+    assert.equal(__rewriteRelativeImportExtension("./foo.TS"), "./foo.js");
+    assert.equal(__rewriteRelativeImportExtension("./foo.Ts"), "./foo.js");
   });
 
   test("rewrites other TypeScript extensions", () => {
@@ -14,6 +16,7 @@ testHelper("__rewriteRelativeImportExtension", __rewriteRelativeImportExtension
     assert.equal(__rewriteRelativeImportExtension("./foo.cts"), "./foo.cjs");
     assert.equal(__rewriteRelativeImportExtension("./foo.tsx"), "./foo.js");
     assert.equal(__rewriteRelativeImportExtension("./foo.tsx", true), "./foo.jsx");
+    assert.equal(__rewriteRelativeImportExtension("./foo.Tsx", true), "./foo.jsx");
   });
 
   test("does not rewrite other extensions", () => {
@@ -45,5 +48,6 @@ testHelper("__rewriteRelativeImportExtension", __rewriteRelativeImportExtension
     assert.equal(__rewriteRelativeImportExtension("./foo.d.mts"), "./foo.d.mts");
     assert.equal(__rewriteRelativeImportExtension("./foo.d.cts"), "./foo.d.cts");
     assert.equal(__rewriteRelativeImportExtension("./foo.d.css.ts"), "./foo.d.css.ts");
+    assert.equal(__rewriteRelativeImportExtension("./foo.D.ts"), "./foo.D.ts");
   });
 });
diff --git a/tslib.es6.js b/tslib.es6.js
index a1323a6..36b58a5 100644
--- a/tslib.es6.js
+++ b/tslib.es6.js
@@ -350,17 +350,18 @@ export function __disposeResources(env) {
 
 export function __rewriteRelativeImportExtension(path, preserveJsx) {
     if (typeof path === "string" && path[0] === "." && (path[1] === "/" || path[1] === "." && path[2] === "/")) {
-        if (path.substring(path.length - 4) === ".tsx") {
+        if (path.substring(path.length - 4).toLowerCase() === ".tsx") {
             return path.substring(0, path.length - 4) + (preserveJsx ? ".jsx" : ".js");
         }
-        if (path.substring(path.length - 3) === ".ts") {
-            var dot = path.lastIndexOf(".", path.length - 4);
-            if (dot >= 0 && (path.substring(dot - 2, dot) === ".d" || path.substring(dot, dot + 2) === ".d")) {
+        var extMatch = path.match(/\.[cm]?ts$/i);
+        if (extMatch) {
+            var ext = extMatch[0].toLowerCase();
+            var dot = path.lastIndexOf(".", path.length - (ext.length + 1));
+            if (dot >= 0 && (path.substring(dot - 2, dot).toLowerCase() === ".d" || path.substring(dot, dot + 2).toLowerCase() === ".d")) {
                 return path;
             }
-            return path.substring(0, path.length - 3) + ".js";
+            return path.substring(0, path.length - ext.length) + (ext === ".mts" ? ".mjs" : ext === ".cts" ? ".cjs" : ".js");
         }
-        return path.replace(/(?<!\.d)\.[cm]ts$/, function (ext) { return ext === ".mts" ? ".mjs" : ".cjs"; });
     }
     return path;
 }
diff --git a/tslib.es6.mjs b/tslib.es6.mjs
index e225e43..ccffef3 100644
--- a/tslib.es6.mjs
+++ b/tslib.es6.mjs
@@ -349,17 +349,18 @@ export function __disposeResources(env) {
 
 export function __rewriteRelativeImportExtension(path, preserveJsx) {
   if (typeof path === "string" && path[0] === "." && (path[1] === "/" || path[1] === "." && path[2] === "/")) {
-    if (path.substring(path.length - 4) === ".tsx") {
-      return path.substring(0, path.length - 4) + (preserveJsx ? ".jsx" : ".js");
-    }
-    if (path.substring(path.length - 3) === ".ts") {
-      var dot = path.lastIndexOf(".", path.length - 4);
-      if (dot >= 0 && (path.substring(dot - 2, dot) === ".d" || path.substring(dot, dot + 2) === ".d")) {
-        return path;
+      if (path.substring(path.length - 4).toLowerCase() === ".tsx") {
+          return path.substring(0, path.length - 4) + (preserveJsx ? ".jsx" : ".js");
+      }
+      var extMatch = path.match(/\.[cm]?ts$/i);
+      if (extMatch) {
+          var ext = extMatch[0].toLowerCase();
+          var dot = path.lastIndexOf(".", path.length - (ext.length + 1));
+          if (dot >= 0 && (path.substring(dot - 2, dot).toLowerCase() === ".d" || path.substring(dot, dot + 2).toLowerCase() === ".d")) {
+              return path;
+          }
+          return path.substring(0, path.length - ext.length) + (ext === ".mts" ? ".mjs" : ext === ".cts" ? ".cjs" : ".js");
       }
-      return path.substring(0, path.length - 3) + ".js";
-    }
-    return path.replace(/(?<!\.d)\.[cm]ts$/, function (ext) { return ext === ".mts" ? ".mjs" : ".cjs"; });
   }
   return path;
 }
diff --git a/tslib.js b/tslib.js
index 6587aa1..64090f0 100644
--- a/tslib.js
+++ b/tslib.js
@@ -398,17 +398,18 @@ var __rewriteRelativeImportExtension;
 
     __rewriteRelativeImportExtension = function (path, preserveJsx) {
         if (typeof path === "string" && path[0] === "." && (path[1] === "/" || path[1] === "." && path[2] === "/")) {
-            if (path.substring(path.length - 4) === ".tsx") {
+            if (path.substring(path.length - 4).toLowerCase() === ".tsx") {
                 return path.substring(0, path.length - 4) + (preserveJsx ? ".jsx" : ".js");
             }
-            if (path.substring(path.length - 3) === ".ts") {
-                var dot = path.lastIndexOf(".", path.length - 4);
-                if (dot >= 0 && (path.substring(dot - 2, dot) === ".d" || path.substring(dot, dot + 2) === ".d")) {
+            var extMatch = path.match(/\.[cm]?ts$/i);
+            if (extMatch) {
+                var ext = extMatch[0].toLowerCase();
+                var dot = path.lastIndexOf(".", path.length - (ext.length + 1));
+                if (dot >= 0 && (path.substring(dot - 2, dot).toLowerCase() === ".d" || path.substring(dot, dot + 2).toLowerCase() === ".d")) {
                     return path;
                 }
-                return path.substring(0, path.length - 3) + ".js";
+                return path.substring(0, path.length - ext.length) + (ext === ".mts" ? ".mjs" : ext === ".cts" ? ".cjs" : ".js");
             }
-            return path.replace(/(?<!\.d)\.[cm]ts$/, function (ext) { return ext === ".mts" ? ".mjs" : ".cjs"; });
         }
         return path;
     };

From e828dac33c7721a8ab16a37200dfb6101958d351 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Tue, 24 Sep 2024 09:38:27 -0700
Subject: [PATCH 3/9] Shorten by one line

---
 tslib.es6.js  | 5 ++---
 tslib.es6.mjs | 5 ++---
 tslib.js      | 5 ++---
 3 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/tslib.es6.js b/tslib.es6.js
index 36b58a5..5b36110 100644
--- a/tslib.es6.js
+++ b/tslib.es6.js
@@ -357,10 +357,9 @@ export function __rewriteRelativeImportExtension(path, preserveJsx) {
         if (extMatch) {
             var ext = extMatch[0].toLowerCase();
             var dot = path.lastIndexOf(".", path.length - (ext.length + 1));
-            if (dot >= 0 && (path.substring(dot - 2, dot).toLowerCase() === ".d" || path.substring(dot, dot + 2).toLowerCase() === ".d")) {
-                return path;
+            if (dot < 0 || !(path.substring(dot - 2, dot).toLowerCase() === ".d" || path.substring(dot, dot + 2).toLowerCase() === ".d")) {
+                return path.substring(0, path.length - ext.length) + (ext === ".mts" ? ".mjs" : ext === ".cts" ? ".cjs" : ".js");
             }
-            return path.substring(0, path.length - ext.length) + (ext === ".mts" ? ".mjs" : ext === ".cts" ? ".cjs" : ".js");
         }
     }
     return path;
diff --git a/tslib.es6.mjs b/tslib.es6.mjs
index ccffef3..7fed569 100644
--- a/tslib.es6.mjs
+++ b/tslib.es6.mjs
@@ -356,10 +356,9 @@ export function __rewriteRelativeImportExtension(path, preserveJsx) {
       if (extMatch) {
           var ext = extMatch[0].toLowerCase();
           var dot = path.lastIndexOf(".", path.length - (ext.length + 1));
-          if (dot >= 0 && (path.substring(dot - 2, dot).toLowerCase() === ".d" || path.substring(dot, dot + 2).toLowerCase() === ".d")) {
-              return path;
+          if (dot < 0 || !(path.substring(dot - 2, dot).toLowerCase() === ".d" || path.substring(dot, dot + 2).toLowerCase() === ".d")) {
+              return path.substring(0, path.length - ext.length) + (ext === ".mts" ? ".mjs" : ext === ".cts" ? ".cjs" : ".js");
           }
-          return path.substring(0, path.length - ext.length) + (ext === ".mts" ? ".mjs" : ext === ".cts" ? ".cjs" : ".js");
       }
   }
   return path;
diff --git a/tslib.js b/tslib.js
index 64090f0..d22e885 100644
--- a/tslib.js
+++ b/tslib.js
@@ -405,10 +405,9 @@ var __rewriteRelativeImportExtension;
             if (extMatch) {
                 var ext = extMatch[0].toLowerCase();
                 var dot = path.lastIndexOf(".", path.length - (ext.length + 1));
-                if (dot >= 0 && (path.substring(dot - 2, dot).toLowerCase() === ".d" || path.substring(dot, dot + 2).toLowerCase() === ".d")) {
-                    return path;
+                if (dot < 0 || !(path.substring(dot - 2, dot).toLowerCase() === ".d" || path.substring(dot, dot + 2).toLowerCase() === ".d")) {
+                    return path.substring(0, path.length - ext.length) + (ext === ".mts" ? ".mjs" : ext === ".cts" ? ".cjs" : ".js");
                 }
-                return path.substring(0, path.length - ext.length) + (ext === ".mts" ? ".mjs" : ext === ".cts" ? ".cjs" : ".js");
             }
         }
         return path;

From a55e9f7a805d9aa489fe29f7acb59fdc19f09472 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Tue, 24 Sep 2024 13:57:49 -0700
Subject: [PATCH 4/9] Do more with a regex

---
 tslib.es6.js  | 11 +++--------
 tslib.es6.mjs | 11 +++--------
 tslib.js      | 11 +++--------
 3 files changed, 9 insertions(+), 24 deletions(-)

diff --git a/tslib.es6.js b/tslib.es6.js
index 5b36110..fc6481a 100644
--- a/tslib.es6.js
+++ b/tslib.es6.js
@@ -353,14 +353,9 @@ export function __rewriteRelativeImportExtension(path, preserveJsx) {
         if (path.substring(path.length - 4).toLowerCase() === ".tsx") {
             return path.substring(0, path.length - 4) + (preserveJsx ? ".jsx" : ".js");
         }
-        var extMatch = path.match(/\.[cm]?ts$/i);
-        if (extMatch) {
-            var ext = extMatch[0].toLowerCase();
-            var dot = path.lastIndexOf(".", path.length - (ext.length + 1));
-            if (dot < 0 || !(path.substring(dot - 2, dot).toLowerCase() === ".d" || path.substring(dot, dot + 2).toLowerCase() === ".d")) {
-                return path.substring(0, path.length - ext.length) + (ext === ".mts" ? ".mjs" : ext === ".cts" ? ".cjs" : ".js");
-            }
-        }
+        return path.replace(/(\.d)?(\.[^./]+?)?\.([cm])?ts$/i, function (m, d, ext, cm) {
+            return d && (ext && !cm || !ext) ? m : ("." + (cm || "").toLowerCase() + "js");
+        });
     }
     return path;
 }
diff --git a/tslib.es6.mjs b/tslib.es6.mjs
index 7fed569..bd46885 100644
--- a/tslib.es6.mjs
+++ b/tslib.es6.mjs
@@ -352,14 +352,9 @@ export function __rewriteRelativeImportExtension(path, preserveJsx) {
       if (path.substring(path.length - 4).toLowerCase() === ".tsx") {
           return path.substring(0, path.length - 4) + (preserveJsx ? ".jsx" : ".js");
       }
-      var extMatch = path.match(/\.[cm]?ts$/i);
-      if (extMatch) {
-          var ext = extMatch[0].toLowerCase();
-          var dot = path.lastIndexOf(".", path.length - (ext.length + 1));
-          if (dot < 0 || !(path.substring(dot - 2, dot).toLowerCase() === ".d" || path.substring(dot, dot + 2).toLowerCase() === ".d")) {
-              return path.substring(0, path.length - ext.length) + (ext === ".mts" ? ".mjs" : ext === ".cts" ? ".cjs" : ".js");
-          }
-      }
+      return path.replace(/(\.d)?(\.[^./]+?)?\.([cm])?ts$/i, function (m, d, ext, cm) {
+          return d && (ext && !cm || !ext) ? m : ("." + (cm || "").toLowerCase() + "js");
+      });
   }
   return path;
 }
diff --git a/tslib.js b/tslib.js
index d22e885..7b627f0 100644
--- a/tslib.js
+++ b/tslib.js
@@ -401,14 +401,9 @@ var __rewriteRelativeImportExtension;
             if (path.substring(path.length - 4).toLowerCase() === ".tsx") {
                 return path.substring(0, path.length - 4) + (preserveJsx ? ".jsx" : ".js");
             }
-            var extMatch = path.match(/\.[cm]?ts$/i);
-            if (extMatch) {
-                var ext = extMatch[0].toLowerCase();
-                var dot = path.lastIndexOf(".", path.length - (ext.length + 1));
-                if (dot < 0 || !(path.substring(dot - 2, dot).toLowerCase() === ".d" || path.substring(dot, dot + 2).toLowerCase() === ".d")) {
-                    return path.substring(0, path.length - ext.length) + (ext === ".mts" ? ".mjs" : ext === ".cts" ? ".cjs" : ".js");
-                }
-            }
+            return path.replace(/(\.d)?(\.[^./]+?)?\.([cm])?ts$/i, function (m, d, ext, cm) {
+                return d && (ext && !cm || !ext) ? m : ("." + (cm || "").toLowerCase() + "js");
+            });
         }
         return path;
     };

From 1c03288ab27b787dc4cc3bc9e002c7d3d1a27815 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Tue, 24 Sep 2024 14:05:56 -0700
Subject: [PATCH 5/9] Test and fix invalid declaration-looking extensions

---
 test/node/rewriteRelativeImportExtension.test.js | 3 +++
 tslib.es6.js                                     | 2 +-
 tslib.es6.mjs                                    | 2 +-
 tslib.js                                         | 2 +-
 4 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/test/node/rewriteRelativeImportExtension.test.js b/test/node/rewriteRelativeImportExtension.test.js
index 25158e1..af69458 100644
--- a/test/node/rewriteRelativeImportExtension.test.js
+++ b/test/node/rewriteRelativeImportExtension.test.js
@@ -9,6 +9,7 @@ testHelper("__rewriteRelativeImportExtension", __rewriteRelativeImportExtension
     assert.equal(__rewriteRelativeImportExtension("../../foo.ts"), "../../foo.js");
     assert.equal(__rewriteRelativeImportExtension("./foo.TS"), "./foo.js");
     assert.equal(__rewriteRelativeImportExtension("./foo.Ts"), "./foo.js");
+    assert.equal(__rewriteRelativeImportExtension("./foo/.hidden/foo.ts"), "./foo/.hidden/foo.js");
   });
 
   test("rewrites other TypeScript extensions", () => {
@@ -17,6 +18,8 @@ testHelper("__rewriteRelativeImportExtension", __rewriteRelativeImportExtension
     assert.equal(__rewriteRelativeImportExtension("./foo.tsx"), "./foo.js");
     assert.equal(__rewriteRelativeImportExtension("./foo.tsx", true), "./foo.jsx");
     assert.equal(__rewriteRelativeImportExtension("./foo.Tsx", true), "./foo.jsx");
+    assert.equal(__rewriteRelativeImportExtension("./foo.d.css.mts"), "./foo.d.css.mjs");
+    assert.equal(__rewriteRelativeImportExtension("./foo.d.tsx"), "./foo.d.js");
   });
 
   test("does not rewrite other extensions", () => {
diff --git a/tslib.es6.js b/tslib.es6.js
index fc6481a..545a8ef 100644
--- a/tslib.es6.js
+++ b/tslib.es6.js
@@ -354,7 +354,7 @@ export function __rewriteRelativeImportExtension(path, preserveJsx) {
             return path.substring(0, path.length - 4) + (preserveJsx ? ".jsx" : ".js");
         }
         return path.replace(/(\.d)?(\.[^./]+?)?\.([cm])?ts$/i, function (m, d, ext, cm) {
-            return d && (ext && !cm || !ext) ? m : ("." + (cm || "").toLowerCase() + "js");
+            return d && (ext && !cm || !ext) ? m : ((d || "") + (ext || "") + "." + (cm || "").toLowerCase() + "js");
         });
     }
     return path;
diff --git a/tslib.es6.mjs b/tslib.es6.mjs
index bd46885..3f7c843 100644
--- a/tslib.es6.mjs
+++ b/tslib.es6.mjs
@@ -353,7 +353,7 @@ export function __rewriteRelativeImportExtension(path, preserveJsx) {
           return path.substring(0, path.length - 4) + (preserveJsx ? ".jsx" : ".js");
       }
       return path.replace(/(\.d)?(\.[^./]+?)?\.([cm])?ts$/i, function (m, d, ext, cm) {
-          return d && (ext && !cm || !ext) ? m : ("." + (cm || "").toLowerCase() + "js");
+          return d && (ext && !cm || !ext) ? m : ((d || "") + (ext || "") + "." + (cm || "").toLowerCase() + "js");
       });
   }
   return path;
diff --git a/tslib.js b/tslib.js
index 7b627f0..88c717f 100644
--- a/tslib.js
+++ b/tslib.js
@@ -402,7 +402,7 @@ var __rewriteRelativeImportExtension;
                 return path.substring(0, path.length - 4) + (preserveJsx ? ".jsx" : ".js");
             }
             return path.replace(/(\.d)?(\.[^./]+?)?\.([cm])?ts$/i, function (m, d, ext, cm) {
-                return d && (ext && !cm || !ext) ? m : ("." + (cm || "").toLowerCase() + "js");
+                return d && (ext && !cm || !ext) ? m : ((d || "") + (ext || "") + "." + (cm || "").toLowerCase() + "js");
             });
         }
         return path;

From 9c731e9f325b1e8341c8fbc3a7ca572cc792f15b Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Tue, 24 Sep 2024 15:18:20 -0700
Subject: [PATCH 6/9] Combine tsx case into regex

---
 tslib.es6.js  | 9 +++------
 tslib.es6.mjs | 9 +++------
 tslib.js      | 9 +++------
 3 files changed, 9 insertions(+), 18 deletions(-)

diff --git a/tslib.es6.js b/tslib.es6.js
index 545a8ef..2c7eaad 100644
--- a/tslib.es6.js
+++ b/tslib.es6.js
@@ -349,12 +349,9 @@ export function __disposeResources(env) {
 }
 
 export function __rewriteRelativeImportExtension(path, preserveJsx) {
-    if (typeof path === "string" && path[0] === "." && (path[1] === "/" || path[1] === "." && path[2] === "/")) {
-        if (path.substring(path.length - 4).toLowerCase() === ".tsx") {
-            return path.substring(0, path.length - 4) + (preserveJsx ? ".jsx" : ".js");
-        }
-        return path.replace(/(\.d)?(\.[^./]+?)?\.([cm])?ts$/i, function (m, d, ext, cm) {
-            return d && (ext && !cm || !ext) ? m : ((d || "") + (ext || "") + "." + (cm || "").toLowerCase() + "js");
+    if (typeof path === "string" && /^\.\.?\//.test(path)) {
+        return path.replace(/\.(tsx)$|(\.d)?(\.[^./]+?)?\.([cm])?ts$/i, function (m, tsx, d, ext, cm) {
+            return tsx ? preserveJsx ? ".jsx" : ".js" : d && (ext && !cm || !ext) ? m : ((d || "") + (ext || "") + "." + (cm || "").toLowerCase() + "js");
         });
     }
     return path;
diff --git a/tslib.es6.mjs b/tslib.es6.mjs
index 3f7c843..9c2c3f3 100644
--- a/tslib.es6.mjs
+++ b/tslib.es6.mjs
@@ -348,12 +348,9 @@ export function __disposeResources(env) {
 }
 
 export function __rewriteRelativeImportExtension(path, preserveJsx) {
-  if (typeof path === "string" && path[0] === "." && (path[1] === "/" || path[1] === "." && path[2] === "/")) {
-      if (path.substring(path.length - 4).toLowerCase() === ".tsx") {
-          return path.substring(0, path.length - 4) + (preserveJsx ? ".jsx" : ".js");
-      }
-      return path.replace(/(\.d)?(\.[^./]+?)?\.([cm])?ts$/i, function (m, d, ext, cm) {
-          return d && (ext && !cm || !ext) ? m : ((d || "") + (ext || "") + "." + (cm || "").toLowerCase() + "js");
+  if (typeof path === "string" && /^\.\.?\//.test(path)) {
+      return path.replace(/\.(tsx)$|(\.d)?(\.[^./]+?)?\.([cm])?ts$/i, function (m, tsx, d, ext, cm) {
+          return tsx ? preserveJsx ? ".jsx" : ".js" : d && (ext && !cm || !ext) ? m : ((d || "") + (ext || "") + "." + (cm || "").toLowerCase() + "js");
       });
   }
   return path;
diff --git a/tslib.js b/tslib.js
index 88c717f..53455fd 100644
--- a/tslib.js
+++ b/tslib.js
@@ -397,12 +397,9 @@ var __rewriteRelativeImportExtension;
     };
 
     __rewriteRelativeImportExtension = function (path, preserveJsx) {
-        if (typeof path === "string" && path[0] === "." && (path[1] === "/" || path[1] === "." && path[2] === "/")) {
-            if (path.substring(path.length - 4).toLowerCase() === ".tsx") {
-                return path.substring(0, path.length - 4) + (preserveJsx ? ".jsx" : ".js");
-            }
-            return path.replace(/(\.d)?(\.[^./]+?)?\.([cm])?ts$/i, function (m, d, ext, cm) {
-                return d && (ext && !cm || !ext) ? m : ((d || "") + (ext || "") + "." + (cm || "").toLowerCase() + "js");
+        if (typeof path === "string" && /^\.\.?\//.test(path)) {
+            return path.replace(/\.(tsx)$|(\.d)?(\.[^./]+?)?\.([cm])?ts$/i, function (m, tsx, d, ext, cm) {
+                return tsx ? preserveJsx ? ".jsx" : ".js" : d && (ext && !cm || !ext) ? m : ((d || "") + (ext || "") + "." + (cm || "").toLowerCase() + "js");
             });
         }
         return path;

From fece22a6b42e378abcf7dfbefaa89b62e0b814f8 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Tue, 24 Sep 2024 15:33:34 -0700
Subject: [PATCH 7/9] Add URL-ish test

---
 test/node/rewriteRelativeImportExtension.test.js | 1 +
 1 file changed, 1 insertion(+)

diff --git a/test/node/rewriteRelativeImportExtension.test.js b/test/node/rewriteRelativeImportExtension.test.js
index af69458..6eb83d5 100644
--- a/test/node/rewriteRelativeImportExtension.test.js
+++ b/test/node/rewriteRelativeImportExtension.test.js
@@ -30,6 +30,7 @@ testHelper("__rewriteRelativeImportExtension", __rewriteRelativeImportExtension
     assert.equal(__rewriteRelativeImportExtension("./foo.json"), "./foo.json");
     assert.equal(__rewriteRelativeImportExtension("./foo.css"), "./foo.css");
     assert.equal(__rewriteRelativeImportExtension("./foo"), "./foo");
+    assert.equal(__rewriteRelativeImportExtension("./foo.d.php?q=1.ts"), "./foo.d.php?q=1.ts");
   });
 
   test("does not rewrite non-relative imports", () => {

From 27b219209a4d35308e9dd6a533e5169a981d2614 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Tue, 24 Sep 2024 16:04:07 -0700
Subject: [PATCH 8/9] Little optimizations

---
 tslib.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tslib.js b/tslib.js
index 53455fd..95beb91 100644
--- a/tslib.js
+++ b/tslib.js
@@ -398,8 +398,8 @@ var __rewriteRelativeImportExtension;
 
     __rewriteRelativeImportExtension = function (path, preserveJsx) {
         if (typeof path === "string" && /^\.\.?\//.test(path)) {
-            return path.replace(/\.(tsx)$|(\.d)?(\.[^./]+?)?\.([cm])?ts$/i, function (m, tsx, d, ext, cm) {
-                return tsx ? preserveJsx ? ".jsx" : ".js" : d && (ext && !cm || !ext) ? m : ((d || "") + (ext || "") + "." + (cm || "").toLowerCase() + "js");
+            return path.replace(/\.(tsx)$|((?:\.d)?)((?:\.[^./]+?)?)\.([cm]?)ts$/i, function (m, tsx, d, ext, cm) {
+                return tsx ? preserveJsx ? ".jsx" : ".js" : d && (!ext || !cm) ? m : (d + ext + "." + cm.toLowerCase() + "js");
             });
         }
         return path;

From c4cde745896b4d845a11dc5aeb72405074c9a0c5 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Tue, 24 Sep 2024 16:52:24 -0700
Subject: [PATCH 9/9] Missed update

---
 tslib.es6.js  | 4 ++--
 tslib.es6.mjs | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/tslib.es6.js b/tslib.es6.js
index 2c7eaad..ddd87f6 100644
--- a/tslib.es6.js
+++ b/tslib.es6.js
@@ -350,8 +350,8 @@ export function __disposeResources(env) {
 
 export function __rewriteRelativeImportExtension(path, preserveJsx) {
     if (typeof path === "string" && /^\.\.?\//.test(path)) {
-        return path.replace(/\.(tsx)$|(\.d)?(\.[^./]+?)?\.([cm])?ts$/i, function (m, tsx, d, ext, cm) {
-            return tsx ? preserveJsx ? ".jsx" : ".js" : d && (ext && !cm || !ext) ? m : ((d || "") + (ext || "") + "." + (cm || "").toLowerCase() + "js");
+        return path.replace(/\.(tsx)$|((?:\.d)?)((?:\.[^./]+?)?)\.([cm]?)ts$/i, function (m, tsx, d, ext, cm) {
+            return tsx ? preserveJsx ? ".jsx" : ".js" : d && (!ext || !cm) ? m : (d + ext + "." + cm.toLowerCase() + "js");
         });
     }
     return path;
diff --git a/tslib.es6.mjs b/tslib.es6.mjs
index 9c2c3f3..a1d9ef5 100644
--- a/tslib.es6.mjs
+++ b/tslib.es6.mjs
@@ -349,8 +349,8 @@ export function __disposeResources(env) {
 
 export function __rewriteRelativeImportExtension(path, preserveJsx) {
   if (typeof path === "string" && /^\.\.?\//.test(path)) {
-      return path.replace(/\.(tsx)$|(\.d)?(\.[^./]+?)?\.([cm])?ts$/i, function (m, tsx, d, ext, cm) {
-          return tsx ? preserveJsx ? ".jsx" : ".js" : d && (ext && !cm || !ext) ? m : ((d || "") + (ext || "") + "." + (cm || "").toLowerCase() + "js");
+      return path.replace(/\.(tsx)$|((?:\.d)?)((?:\.[^./]+?)?)\.([cm]?)ts$/i, function (m, tsx, d, ext, cm) {
+          return tsx ? preserveJsx ? ".jsx" : ".js" : d && (!ext || !cm) ? m : (d + ext + "." + cm.toLowerCase() + "js");
       });
   }
   return path;