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wraithgar merged 1 commit into from
Dec 17, 2025
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docs(npm-install): explain package-lock.json behavior #8797

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12 changes: 12 additions & 0 deletions docs/lib/content/commands/npm-install.md
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Expand Up @@ -19,6 +19,18 @@ If the package has a package-lock, or an npm shrinkwrap file, or a yarn lock fil

See [package-lock.json](/configuring-npm/package-lock-json) and [`npm shrinkwrap`](/commands/npm-shrinkwrap).

#### How `npm install` uses `package-lock.json`

When you run `npm install` without arguments, npm compares `package.json` and `package-lock.json`:

* **If the lockfile's resolved versions satisfy the `package.json` ranges:** npm uses the exact versions from `package-lock.json` to ensure reproducible builds across environments.

* **If the ranges don't match:** npm resolves new versions that satisfy the `package.json` ranges and updates `package-lock.json` accordingly. This happens when you modify version ranges in `package.json` (e.g., changing `^7.0.0` to `^8.0.0`). Note that changing a range within the same major version (e.g., `^7.0.0` to `^7.1.0`) will only update the metadata in the lockfile if the currently installed version still satisfies the new range.

In essence, `package-lock.json` locks your dependencies to specific versions, but `package.json` is the source of truth for acceptable version ranges. When the lockfile's versions satisfy the `package.json` ranges, the lockfile wins. When they conflict, `package.json` wins and the lockfile is updated.

If you want to install packages while ensuring that `package.json` is not modified and that both files are strictly in sync, use [`npm ci`](/commands/npm-ci) instead.

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@wraithgar wraithgar Dec 12, 2025

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We probably want to explain the way to NOT have npm change these files:

"If you want to install packages and ensure that these files match, and that npm will not change your package.json, consider running npm ci"

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@MaxBlack-dev MaxBlack-dev Dec 12, 2025

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Great suggestion! I've added a paragraph at the end of the section recommending npm ci for users who want to ensure strict synchronization without npm modifying package.json. This provides a clear path for those who need that behavior.

A `package` is:

* a) a folder containing a program described by a [`package.json`](/configuring-npm/package-json) file
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