Improve warning

Author: GeoffreyBooth

lib/internal/modules/esm/loader.js

@@ -4,7 +4,10 @@
 require('internal/modules/cjs/loader');
 
 const {
+  ArrayPrototypeJoin,
+  ArrayPrototypeMap,
   FunctionPrototypeCall,
+  JSONStringify,
   ObjectSetPrototypeOf,
   SafeWeakMap,
 } = primordials;
@@ -516,7 +519,11 @@ function createModuleLoader(useCustomLoadersIfPresent = true) {
     if (userLoaderPaths.length > 0) {
       if (!emittedLoaderFlagWarning) {
         process.emitWarning(
-          '`--experimental-loader` may be removed in the future; instead use `--import` to reference a file that calls `register()`',
+          '`--experimental-loader` may be removed in the future; instead use `register()`:\n' +
+          `--import 'data:text/javascript,import { register } from "node:module"; import { pathToFileURL } from "node:url"; ${ArrayPrototypeJoin(
+            ArrayPrototypeMap(userLoaderPaths, (loader) => `register(${JSONStringify(encodeURI(loader))}, pathToFileURL("./"))`),
+            "; ",
+          )};'`,
           'ExperimentalWarning',
         );
         emittedLoaderFlagWarning = true;