{"id":1583,"date":"2026-07-03T07:40:56","date_gmt":"2026-07-03T07:40:56","guid":{"rendered":"https:\/\/razvanvancea.ro\/blog\/?p=1583"},"modified":"2026-07-03T07:46:06","modified_gmt":"2026-07-03T07:46:06","slug":"using-npm-prefix-to-run-scripts-from-a-nested-package-json","status":"publish","type":"post","link":"https:\/\/razvanvancea.ro\/blog\/2026\/07\/03\/using-npm-prefix-to-run-scripts-from-a-nested-package-json\/","title":{"rendered":"Using npm –prefix to Run Scripts from a Nested package.json"},"content":{"rendered":"
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npm has an interesting flag called --prefix<\/code> that can be useful when you have multiple package.json<\/code> files in the same project.<\/p>

A practical example is the following structure:<\/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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project-root\/ 
    package.json 
    tests\/ package.json<\/pre>\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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In the project root, you may have a package.json<\/code> dedicated to development-related packages, such as build tools, linting, formatting, or other general project scripts.<\/p>
Separately, the project may contain a tests<\/code> folder with its own package.json<\/code>, dedicated to test-related packages. For example, this is where you might keep dependencies and scripts for Playwright, Cypress, or other automated testing tools.<\/p>
Both package.json<\/code> files can define their own scripts.<\/p>
For example, in tests\/package.json<\/code>, you might have:<\/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\"tests-pw\"\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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A commonly used approach, when running the command from the project root, is:<\/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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cd tests && npm run e2e<\/pre>\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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This works, but it requires changing the current directory before running the script.<\/p>
An alternative approach is to use --prefix<\/code> directly from the project root:<\/p>
<\/code><\/pre>\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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npm --prefix tests run e2e<\/pre>\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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In the example above, tests<\/code> is the path to the folder that contains the target package.json<\/code>, and e2e<\/code> is the script defined inside tests\/package.json<\/code>.<\/p>
In other words, you are telling npm: \u201crun this command in the context of this folder.\u201d

One benefit is that you can also expose this from the root package.json<\/code>:<\/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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Then, from the project root, you can simply run:<\/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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npm run e2e<\/pre>\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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and npm will execute the e2e<\/code> script defined in tests\/package.json<\/code>.<\/p>
It is a small detail, but a useful one, especially in projects where automated tests are organized as a separate sub-project with their own dependencies and scripts.<\/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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Enjoyed this article?
I share more practical automation tips on\u00a0YouTube<\/strong><\/a>\u00a0and\u00a0LinkedIn<\/strong><\/a>.<\/p>
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Or email me at\u00a0iamqarv [at] gmail [dot] com<\/strong><\/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":"
npm has an interesting flag called –prefix that can be useful when you have multiple…<\/p>\n","protected":false},"author":2,"featured_media":0,"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-1583","post","type-post","status-publish","format-standard","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