worker_threads: add type option to new Worker()

Allows eval of ESM string.

Fixes: nodejs#30682

doc/api/worker_threads.md

@@ -561,14 +561,15 @@ if (isMainThread) {
 <!-- YAML
 added: v10.5.0
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/31760
+    description: The `type` option was introduced.
   - version:
      - v13.13.0
      - v12.17.0
     pr-url: https://github.com/nodejs/node/pull/32278
     description: The `transferList` option was introduced.
-  - version:
-     - v13.12.0
-     - v12.17.0
+  - version: v13.12.0
     pr-url: https://github.com/nodejs/node/pull/31664
     description: The `filename` parameter can be a WHATWG `URL` object using
                  `file:` protocol.
@@ -600,9 +601,12 @@ changes:
     to specify that the parent thread and the child thread should share their
     environment variables; in that case, changes to one thread’s `process.env`
     object will affect the other thread as well. **Default:** `process.env`.
-  * `eval` {boolean} If `true` and the first argument is a `string`, interpret
-    the first argument to the constructor as a script that is executed once the
-    worker is online.
+  * `eval` {boolean} If `true`, interpret the first argument to the constructor
+    as a script (or a module if `type` is set to `module`) that is executed once
+    the worker is online.
+  * `type` {string} If `"module"` and `eval` is set to `true`, interpret the
+    first argument as an ECMAScript 2015 module instead of a script. The default
+    value is `"classic"`. Doesn't have any effect when `eval` is set to `false`.
   * `execArgv` {string[]} List of node CLI options passed to the worker.
     V8 options (such as `--max-old-space-size`) and options that affect the
     process (such as `--title`) are not supported. If set, this will be provided

lib/internal/main/worker_thread.js

@@ -4,6 +4,7 @@
 // message port.
 
 const {
+  ArrayPrototypeSplice,
   ObjectDefineProperty,
 } = primordials;
 
@@ -98,6 +99,7 @@ port.on('message', (message) => {
       cwdCounter,
       filename,
       doEval,
+      workerType,
       workerData,
       publicPort,
       manifestSrc,
@@ -148,17 +150,24 @@ port.on('message', (message) => {
           `(eval = ${eval}) at cwd = ${process.cwd()}`);
     port.postMessage({ type: UP_AND_RUNNING });
     if (doEval) {
-      const { evalScript } = require('internal/process/execution');
-      const name = '[worker eval]';
-      // This is necessary for CJS module compilation.
-      // TODO: pass this with something really internal.
-      ObjectDefineProperty(process, '_eval', {
-        configurable: true,
-        enumerable: true,
-        value: filename,
-      });
-      process.argv.splice(1, 0, name);
-      evalScript(name, filename);
+      if (workerType === 'module') {
+        const { evalModule } = require('internal/process/execution');
+        evalModule(filename).catch((e) => {
+          workerOnGlobalUncaughtException(e, true);
+        });
+      } else {
+        const { evalScript } = require('internal/process/execution');
+        const name = '[worker eval]';
+        // This is necessary for CJS module compilation.
+        // TODO: pass this with something really internal.
+        ObjectDefineProperty(process, '_eval', {
+          configurable: true,
+          enumerable: true,
+          value: filename,
+        });
+        ArrayPrototypeSplice(process.argv, 1, 0, name);
+        evalScript(name, filename);
+      }
     } else {
       // script filename
       // runMain here might be monkey-patched by users in --require.

lib/internal/worker.js

@@ -44,6 +44,7 @@ const {
 } = workerIo;
 const { deserializeError } = require('internal/error-serdes');
 const { fileURLToPath, isURLInstance, pathToFileURL } = require('internal/url');
+const { validateString } = require('internal/validators');
 
 const {
   ownsProcessState,
@@ -130,6 +131,16 @@ class Worker extends EventEmitter {
         throw new ERR_WORKER_UNSUPPORTED_EXTENSION(ext);
       }
     }
+    if (options.type) {
+      validateString(options.type, 'options.type');
+      if (options.type !== 'module' && options.type !== 'classic') {
+        throw new ERR_INVALID_ARG_VALUE(
+          'options.type',
+          options.type,
+          'must be either "module" or "classic"'
+        );
+      }
+    }
 
     let env;
     if (typeof options.env === 'object' && options.env !== null) {
@@ -197,6 +208,7 @@ class Worker extends EventEmitter {
       type: messageTypes.LOAD_SCRIPT,
       filename,
       doEval: !!options.eval,
+      workerType: options.type,
       cwdCounter: cwdCounter || workerIo.sharedCwdCounter,
       workerData: options.workerData,
       publicPort: port2,

test/parallel/test-worker-eval.js

@@ -0,0 +1,38 @@
+'use strict';
+require('../common');
+const assert = require('assert');
+const { Worker } = require('worker_threads');
+
+const moduleString = 'export default import.meta.url;';
+const cjsString = 'module.exports=__filename;';
+
+const cjsLoadingESMError = /Unexpected token 'export'/;
+const esmLoadingCJSError = /module is not defined/;
+const invalidValueError =
+  /The argument 'options\.type' must be either "module" or "classic"/;
+
+function runInWorker(evalString, options) {
+  return new Promise((resolve, reject) => {
+    const worker = new Worker(evalString, options);
+    worker.on('error', reject);
+    worker.on('exit', resolve);
+  });
+}
+
+let options;
+
+options = { eval: true };
+assert.rejects(runInWorker(moduleString, options), cjsLoadingESMError);
+runInWorker(cjsString, options); // does not reject
+
+options = { eval: true, type: 'classic' };
+assert.rejects(runInWorker(moduleString, options), cjsLoadingESMError);
+runInWorker(cjsString, options); // does not reject
+
+options = { eval: true, type: 'module' };
+runInWorker(moduleString, options); // does not reject
+assert.rejects(runInWorker(cjsString, options), esmLoadingCJSError);
+
+options = { eval: true, type: 'wasm' };
+assert.rejects(runInWorker(moduleString, options), invalidValueError);
+assert.rejects(runInWorker(cjsString, options), invalidValueError);

test/parallel/test-worker-type-check.js

@@ -27,3 +27,22 @@ const { Worker } = require('worker_threads');
     );
   });
 }
+
+{
+  [
+    Symbol('test'),
+    {},
+    [],
+    () => {}
+  ].forEach((type) => {
+    assert.throws(
+      () => new Worker('', { type, eval: true }),
+      {
+        code: 'ERR_INVALID_ARG_TYPE',
+        name: 'TypeError',
+        message: 'The "options.type" property must be of type string.' +
+                 common.invalidArgTypeHelper(type)
+      }
+    );
+  });
+}