{"id":1201,"date":"2025-08-07T07:50:59","date_gmt":"2025-08-07T07:50:59","guid":{"rendered":"https:\/\/razvanvancea.ro\/blog\/?p=1201"},"modified":"2025-08-13T13:47:43","modified_gmt":"2025-08-13T13:47:43","slug":"understanding-the-difference-between-module-and-commonjs-in-package-json","status":"publish","type":"post","link":"https:\/\/razvanvancea.ro\/blog\/2025\/08\/07\/understanding-the-difference-between-module-and-commonjs-in-package-json\/","title":{"rendered":"Understanding the Difference Between “module” and “commonjs” in package.json"},"content":{"rendered":"
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If you’ve been already working with JavaScript, you’re not alone in feeling confused about the differences between CommonJS and ES Modules (ESM) – especially when it comes to how the “type” field in package.json affects your project.<\/p>

This post breaks down what that field actually does, how it impacts import\/export syntax.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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What does 'type' in package.json actually do?<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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Since Node v14, you can use ECMAScript Modules (ESM) natively – no transpiler needed<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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This tells Node.js how to interpret .js files in your project<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\"\"\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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so: the “type” field only affects .js<\/strong> files<\/strong>, not .mjs or .cjs<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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What are CommonJS and ES Modules (ESM)?<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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CommonJS<\/strong> – the traditional module system used in NodeJS<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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ES Modules (ESM)<\/strong> – the modern, standard way of defining modules in both browser and NodeJS<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\"esm-example\"\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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Conclusion<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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The “type” field in package.json is a switch that tells NodeJS how to handle .js files in your project: either as CommonJS (require\/module.exports) or ES Modules (import\/export).<\/p>

Choosing between them depends on your tooling, the libraries you use, or whether you’re writing for modern or legacy environments.<\/p>

If you’re starting a new project and using modern tooling, go with ESM. But if you are in a legacy environment or rely heavily on require, momentarily it is fine to stick with CommonJS.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"

If you’ve been already working with JavaScript, you’re not alone in feeling confused about the…<\/p>\n","protected":false},"author":2,"featured_media":1231,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":false},"categories":[10],"tags":[],"class_list":["post-1201","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-programming"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t