How to import a Javascript file that is ESM from a CommonJS module? Gulp. Error: [ERR_REQUIRE_ESM]

Question

My project is entirely written as CommonJS module and I don't plan to change it. The problem is that I have to use a library that is ESM when using gulp.

The file where this situation appears:

const { dest, src } = require('gulp')
const imagemin = require('gulp-imagemin') // This is a ESM. Compiler gives error [ERR_REQUIRE_ESM]


const images = () => {
    // We have specific configs for jpeg and png files to try
    // to really pull down asset sizes
    return src('./src/images/**/*')
        .pipe(
            imagemin(
                [
                    imagemin.mozjpeg({ quality: 60, progressive: true }),
                    imagemin.optipng({ optimizationLevel: 5, interlaced: null })
                ],
                {
                    silent: true
                }
            )
        )
        .pipe(dest('./dist/images'))
}

module.exports = images

This is the error that node gives

Error [ERR_REQUIRE_ESM]: require() of ES Module C:\Users\Lucas\Documents\repos\nexus-materiales\node_modules\gulp-imagemin\index.js from C:\Users\Lucas\Documents\repos\nexus-materiales\gulp-tasks\images.js not supported.
Instead change the require of index.js in C:\Users\Lucas\Documents\repos\nexus-materiales\gulp-tasks\images.js to a dynamic import() which is available in all CommonJS modules.
    at Object.<anonymous> (C:\Users\Lucas\Documents\repos\nexus-materiales\gulp-tasks\images.js:2:18)
    at Object.<anonymous> (C:\Users\Lucas\Documents\repos\nexus-materiales\gulpfile.js:4:16)
    at async Promise.all (index 0) {
  code: 'ERR_REQUIRE_ESM'
}

So, How could I include this file using commonJS if it's an ESM? Is this possible?

Atencio

Answer 1

To import an ES module from CommonJS code, use a dynamic import.

ES module imports are asynchronous: you'll have to make sure that the gulp-imagemin import has completed before creating the gulp stream. This can be achieved with gulp.series.

const { dest, series, src } = require('gulp');
let imagemin;

const images = series(
    async () => {
        imagemin = await import('gulp-imagemin');
    },
    () => src('./src/images/**/*')
        .pipe(
            imagemin.default(
                [
                    imagemin.mozjpeg({ quality: 60, progressive: true }),
                    imagemin.optipng({ optimizationLevel: 5, interlaced: null })
                ],
                {
                    silent: true
                }
            )
        )
        .pipe(dest('./dist/images'))
);

Note that I used imagemin.default to access the default export of gulp-imagemin, since it's being imported dynamically.

Causeway

Thanks for pointing out gulp.series which is specific to this case. – Atencio

How do you resolve the async completion on this one? I'm having some difficulty figuring it out. – Octachord