modules icon indicating copy to clipboard operation
modules copied to clipboard

Improve error message when attempting to require(esm)

Open dfabulich opened this issue 5 years ago • 0 comments

// foo.mjs
export const foo = 'bar';

// index.js
require('./foo.mjs');
$ node index.js
internal/modules/cjs/loader.js:1047
    throw new ERR_REQUIRE_ESM(filename);
    ^

Error [ERR_REQUIRE_ESM]: Must use import to load ES Module: /tmp/foo.mjs
    at Module.load (internal/modules/cjs/loader.js:1047:11)
    at Function.Module._load (internal/modules/cjs/loader.js:937:14)
    at Module.require (internal/modules/cjs/loader.js:1089:19)
    at require (internal/modules/cjs/helpers.js:73:18)
    at Object.<anonymous> (/tmp/1/index.js:1:1)
    at Module._compile (internal/modules/cjs/loader.js:1200:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1220:10)
    at Module.load (internal/modules/cjs/loader.js:1049:32)
    at Function.Module._load (internal/modules/cjs/loader.js:937:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12) {
  code: 'ERR_REQUIRE_ESM'
}
  1. The message "Must use import to load ES Module" won't mean anything to users who don't understand the difference between CJS and ESM. If anything, I think it would encourage them to try import './foo.mjs' which is not going to work in a CJS script.

    I suggest something like:

    Error [ERR_REQUIRE_ESM]: This is an ES Module; it can't be loaded with require: /tmp/foo.mjs You can import it asynchronously with import(), or you can import it from an ES Module. See [link]

  2. The top part of this stack points to internal/modules/cjs/loader.js; it should point to index.js

dfabulich avatar May 30 '20 23:05 dfabulich