esm: make dynamic import work in the REPL

lib/repl.js

@@ -279,6 +279,12 @@ function REPLServer(prompt,
   }
 
   function defaultEval(code, context, file, cb) {
+    const { getOptionValue } = require('internal/options');
+    const experimentalModules = getOptionValue('--experimental-modules');
+    const asyncESM = experimentalModules ?
+      require('internal/process/esm_loader') :
+      null;
+
     let result, script, wrappedErr;
     let err = null;
     let wrappedCmd = false;
@@ -312,6 +318,12 @@ function REPLServer(prompt,
     if (code === '\n')
       return cb(null);
 
+    let pwd;
+    try {
+      const { pathToFileURL } = require('url');
+      pwd = pathToFileURL(process.cwd()).href;
+    } catch {
+    }
     while (true) {
       try {
         if (!/^\s*$/.test(code) &&
@@ -322,7 +334,12 @@ function REPLServer(prompt,
         }
         script = vm.createScript(code, {
           filename: file,
-          displayErrors: true
+          displayErrors: true,
+          importModuleDynamically: experimentalModules ?
+            async (specifier) => {
+              return (await asyncESM.loaderPromise).import(specifier, pwd);
+            } :
+            undefined
         });
       } catch (e) {
         debug('parse error %j', code, e);

test/es-module/test-esm-repl.js

@@ -0,0 +1,19 @@
+'use strict';
+require('../common');
+const assert = require('assert');
+const { spawn } = require('child_process');
+
+const child = spawn(process.execPath, [
+  '--experimental-modules',
+  '--interactive'
+]);
+child.stdin.end(`
+import('fs').then(
+  ns => ns.default === require('fs') ? 0 : 1,
+  _ => 2
+).then(process.exit)
+`);
+
+child.on('exit', (code) => {
+  assert.strictEqual(code, 0);
+});