From 9c4b462bb80b09fdaee3564447e6e5df190e7cbc Mon Sep 17 00:00:00 2001
From: calebboyd <caleb.boyd@gmail.com>
Date: Thu, 3 Jun 2021 12:16:40 -0500
Subject: [PATCH] feat(register): try-ts-ext register option

---
 package.json           |  1 +
 register/try-ts-ext.js |  3 +++
 src/index.ts           | 13 ++++++++++++-
 3 files changed, 16 insertions(+), 1 deletion(-)
 create mode 100644 register/try-ts-ext.js

diff --git a/package.json b/package.json
index 76dbbe56f..7cb0a54b3 100644
--- a/package.json
+++ b/package.json
@@ -19,6 +19,7 @@
     "./register/files": "./register/files.js",
     "./register/transpile-only": "./register/transpile-only.js",
     "./register/type-check": "./register/type-check.js",
+    "./register/try-ts-ext": "./register/try-ts-ext.js",
     "./esm": "./esm.mjs",
     "./esm.mjs": "./esm.mjs",
     "./esm/transpile-only": "./esm/transpile-only.mjs",
diff --git a/register/try-ts-ext.js b/register/try-ts-ext.js
new file mode 100644
index 000000000..e2d59618b
--- /dev/null
+++ b/register/try-ts-ext.js
@@ -0,0 +1,3 @@
+require('../dist').register({
+  tryTsExt: true,
+});
diff --git a/src/index.ts b/src/index.ts
index e9b42eac2..29c845f10 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -84,6 +84,7 @@ export interface ProcessEnv {
   TS_NODE_SKIP_PROJECT?: string;
   TS_NODE_SKIP_IGNORE?: string;
   TS_NODE_PREFER_TS_EXTS?: string;
+  TS_NODE_TRY_TS_EXT?: string;
   TS_NODE_IGNORE_DIAGNOSTICS?: string;
   TS_NODE_TRANSPILE_ONLY?: string;
   TS_NODE_TYPE_CHECK?: string;
@@ -280,6 +281,13 @@ export interface RegisterOptions extends CreateOptions {
    * @default false
    */
   preferTsExts?: boolean;
+
+  /**
+   * Attempt to resolve the typescript file when the js file cannot be found.
+   *
+   * @default false
+   */
+  tryTsExt?: boolean
 }
 
 /**
@@ -327,6 +335,7 @@ export const DEFAULTS: RegisterOptions = {
   skipProject: yn(env.TS_NODE_SKIP_PROJECT),
   skipIgnore: yn(env.TS_NODE_SKIP_IGNORE),
   preferTsExts: yn(env.TS_NODE_PREFER_TS_EXTS),
+  tryTsExt: yn(env.TS_NODE_ESM_COMPAT),
   ignoreDiagnostics: split(env.TS_NODE_IGNORE_DIAGNOSTICS),
   transpileOnly: yn(env.TS_NODE_TRANSPILE_ONLY),
   typeCheck: yn(env.TS_NODE_TYPE_CHECK),
@@ -441,7 +450,9 @@ export function register(opts: RegisterOptions = {}): Service {
     originalJsHandler
   );
 
-  patchResolveFileName();
+  if (service.options.tryTsExt) {
+    patchResolveFileName();
+  }
 
   // Require specified modules before start-up.
   (Module as any)._preloadModules(service.options.require);