We're converting our gulpfile.js in node v13.8.0 to ES6 as following:

import { src, dest, series, parallel, watch } from 'gulp'
import nodemon from 'gulp-nodemon' // normal nodemon does not display an error on app crash
import env from 'gulp-env'
import browser from 'browser-sync'
import sass from 'gulp-sass'
// Tasks
export default {
    cssTranspile: cssTranspile,
    jsTranspile: jsTranspile,
    server: series(startNodemon, startBrowserSync),
    default: series(
        parallel(
            cssTranspile,
            jsTranspile
        ),
        startNodemon,
        startBrowserSync,
        function () {
            watch('public/scss/*.scss', cssTranspile)
        }
    )
}

The error reported, when simply running gulp, is:

internal/modules/cjs/loader.js:1160
      throw new ERR_REQUIRE_ESM(filename, parentPath, packageJsonPath);
      ^

Error [ERR_REQUIRE_ESM]: Must use import to load ES Module: T:\Node\ICP\gulpfile.js
require() of ES modules is not supported.

I must be doing something wrong. Anyone an idea on what it might be?

CLI version: 2.2.0
Local version: 4.0.2

The flag "type": "module", is set in package.json as described in the note docs. The issue is very much similar to this issue in the geolib library.

And when we rename gulpfile.js to gulpfile.babel.js as described here we get the same error.

The package.json contain these packages:

  "devDependencies": {
    "@babel/core": "^7.8.4",
    "@babel/preset-env": "^7.8.4",
    "@babel/register": "^7.8.3",
    "exports-loader": "^0.7.0",
    "gulp": "^4.0.2",
    "gulp-env": "^0.4.0",
    "gulp-nodemon": "^2.4.2",
    "gulp-sass": "^4.0.2",
    "nodemon": "^2.0.2"
  },
  "type": "module",
  "babel": {
    "presets": [
      "@babel/env"
    ]

We're converting our gulpfile.js in node v13.8.0 to ES6 as following:

import { src, dest, series, parallel, watch } from 'gulp'
import nodemon from 'gulp-nodemon' // normal nodemon does not display an error on app crash
import env from 'gulp-env'
import browser from 'browser-sync'
import sass from 'gulp-sass'
// Tasks
export default {
    cssTranspile: cssTranspile,
    jsTranspile: jsTranspile,
    server: series(startNodemon, startBrowserSync),
    default: series(
        parallel(
            cssTranspile,
            jsTranspile
        ),
        startNodemon,
        startBrowserSync,
        function () {
            watch('public/scss/*.scss', cssTranspile)
        }
    )
}

The error reported, when simply running gulp, is:

internal/modules/cjs/loader.js:1160
      throw new ERR_REQUIRE_ESM(filename, parentPath, packageJsonPath);
      ^

Error [ERR_REQUIRE_ESM]: Must use import to load ES Module: T:\Node\ICP\gulpfile.js
require() of ES modules is not supported.

I must be doing something wrong. Anyone an idea on what it might be?

CLI version: 2.2.0
Local version: 4.0.2

The flag "type": "module", is set in package.json as described in the note docs. The issue is very much similar to this issue in the geolib library.

And when we rename gulpfile.js to gulpfile.babel.js as described here we get the same error.

The package.json contain these packages:

  "devDependencies": {
    "@babel/core": "^7.8.4",
    "@babel/preset-env": "^7.8.4",
    "@babel/register": "^7.8.3",
    "exports-loader": "^0.7.0",
    "gulp": "^4.0.2",
    "gulp-env": "^0.4.0",
    "gulp-nodemon": "^2.4.2",
    "gulp-sass": "^4.0.2",
    "nodemon": "^2.0.2"
  },
  "type": "module",
  "babel": {
    "presets": [
      "@babel/env"
    ]

• javascript
• node.js
• gulp

• Have you tried renaming gulpfile.js to gulpfile.mjs, then using the --gulpfile gulpfile.mjs flag on the mand line? Maybe that will force loader.js to use import. – terrymorse Commented Feb 13, 2020 at 14:38
• I just tried your suggestion gulp --gulpfile gulpfile.mjs but it returns the same error Error [ERR_REQUIRE_ESM]: Must use import to load ES Module: T:\ICP\gulpfile.mjs – DarkLite1 Commented Feb 13, 2020 at 14:46
• Hmm. Maybe there's a bug in Node's loader.js. that's forcing it to use require. They do warn that import/export are experimental. Here's where that error is ing from: if (filename.endsWith('.mjs') && !Module._extensions['.mjs']) { throw new ERR_REQUIRE_ESM(filename); } – terrymorse Commented Feb 13, 2020 at 16:40
• 1 If the "modules" you are importing don't use es6 import/exports you will have to do extra work to get them to work, see stackoverflow./questions/45854169/… last answer. – Mark Commented Feb 14, 2020 at 3:18
• Thank you @Mark, I opened an issue with gulp to see what can be done. – DarkLite1 Commented Feb 14, 2020 at 8:28

2 Answers 2

In an answer to my own question, when the flag "type": "module" is set in package.json you can't use gulp. More info can be found here.

This seems to be fixed now: https://github./gulpjs/gulp-cli/pull/214. Be sure to install the latest version of gulp-cli (2.3.0 as of June 2020).

If your package.json specifies "type": "module" you can name your ES module with Gulp tasks gulpfile.js, otherwise name it gulpfile.mjs. No need to use any transpilers or preloaders like esm, Babel or TypeScript.