Experimental modules warning does not show when using dynamic import #30601

Activity

1. guybedford

   added

   esmIssues and PRs related to the ECMAScript Modules implementation.Issues and PRs related to the ECMAScript Modules implementation.

   on Nov 22, 2019
2. coreyfarrell commented on Nov 22, 2019

   

   coreyfarrell

   on Nov 22, 2019

   Member

   More actions

   From looking at this code I suspect we cannot prevent the warning if import('./nyc.config.js') loads a CJS file? This makes me lean towards just not supporting nyc.config.js when type: 'module' is specified.
3. guybedford

   added

   good first issueIssues that are suitable for first-time contributors.Issues that are suitable for first-time contributors.

   help wantedIssues that need assistance from volunteers or PRs that need help to proceed.Issues that need assistance from volunteers or PRs that need help to proceed.

   on Nov 25, 2019
4. juanarbol commented on Nov 28, 2019

   

   juanarbol

   on Nov 28, 2019

   Member

   More actions

   How can I recreate this?

   I've change esm_loader.js, hard coded warning:

   exports.importModuleDynamicallyCallback = async function(wrap, specifier) {
     assert(calledInitialize === true || !userLoader);
     process.emitWarning(
       'The ESM module loader is experimental.',
       'ExperimentalWarning', undefined);
     const { callbackMap } = internalBinding('module_wrap');
     if (callbackMap.has(wrap)) {
       const { importModuleDynamically } = callbackMap.get(wrap);
       if (importModuleDynamically !== undefined) {
         return importModuleDynamically(
           specifier, getModuleFromWrap(wrap) || wrap);
       }
     }
     throw new ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING();
   };

   $ ./node mod/file.js
   node:6329) ExperimentalWarning: The ESM module loader is experimental.
   (node:6329) ExperimentalWarning: The ESM module loader is experimental.
   [Module] { default: [Function: default] }

   The warning is already emitted on another place, so it appears two times.
5. coreyfarrell commented on Nov 29, 2019

   

   coreyfarrell

   on Nov 29, 2019

   Member

   More actions

   @juamedgod create two files:

   // test.cjs
   import('./test.mjs')
     .then(console.log)
     .catch(e => console.error(e.message));

   /// test.mjs
   export default 'test.mjs';

   Then run ./node ./test.cjs. Output on current master branch:

   [Module] { default: 'test.mjs' }
   
6. guybedford

   closed this as completedon Dec 7, 2019