A brief analysis of how to call commonjs module in node esmodule mode

This article will continue the learning ofnodeand introduce how to call the commonjs module in esmodule mode. I hope it will be helpful to everyone!

I have been writing a lot ofnodejsscripts recently and encountered a problem. After modifying the type: "module" of package.json, some tools cannot be used normally (e.g. postcss-cli).

This article mainly records and solves the problem of how to use commonjs module in esmodule mode.

Solution

1. Replace the plug-in;

seems to be nonsense, but it is not. Let’s take postcss as an example. In fact,issuehas been followed up for a long time, but it has not been updated yet. I have seen re-implementations such as postcss-es-modules (the download volume is not high, so I haven’t tried it yet).

Or use plug-ins through the support of the vite/rollup framework itself (I will talk about how the framework itself handles it later), e.g.

// tailwind.config.js export default { purge: ['./*.html', './src/**/*.{vue,js,ts,jsx,tsx,css}'], darkMode: false, // or 'media' or 'class' theme: { extend: {}, }, variants: { extend: {}, }, plugins: [], } // postcss.config.js import tailwind from 'tailwindcss' import autoprefixer from 'autoprefixer' import tailwindConfig from './tailwind.config.js' export default { plugins: [tailwind(tailwindConfig), autoprefixer], } // vite.config.js css: { postcss, }

2. Extension methods supported by nodejs (type: " module"), change the file suffix to .cjs, and then you can import the commonjs module through import default from '*.cjs'; e.g.

// utils.cjs function sum(a, b) { return a + b } module.exports = { sum } // index.js import utils from './utils.js' console.log(utils.sum(1, 2))

3. Use the exports field of package.json to mark different The entry file of the module (this is also a common practice for most third-party libraries); e.g.

// package.json "exports": { "import": "./index.js", "require": "./index.cjs" }

Problem record

1. How does nodejs handle the .mjs/.cjs suffix? File?

Nodejs always loads .mjs files with the esmodule module and .cjs files with commonjs. When package.json is set to type: "module", .js files are always loaded as esmodule.

For more node-related knowledge, please visit:nodejs tutorial!

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