* `npmDepsHash`: The output hash of the dependencies for this project. Can be calculated in advance with [`prefetch-npm-deps`](#javascript-buildNpmPackage-prefetch-npm-deps).
* `makeCacheWritable`: Whether to make the cache writable prior to installing dependencies. Don't set this unless npm tries to write to the cache directory, as it can slow down the build.
* `npmBuildScript`: The script to run to build the project. Defaults to `"build"`.
* `npmWorkspace`: The workspace directory within the project to build and install.
* `dontNpmBuild`: Option to disable running the build script. Set to `true` if the package does not have a build script. Defaults to `false`. Alternatively, setting `buildPhase` explicitly also disables this.
* `dontNpmInstall`: Option to disable running `npm install`. Defaults to `false`. Alternatively, setting `installPhase` explicitly also disables this.
* `npmFlags`: Flags to pass to all npm commands.
* `npmInstallFlags`: Flags to pass to `npm ci`.
* `npmBuildFlags`: Flags to pass to `npm run ${npmBuildScript}`.
* `npmPackFlags`: Flags to pass to `npm pack`.
* `npmPruneFlags`: Flags to pass to `npm prune`. Defaults to the value of `npmInstallFlags`.
* `makeWrapperArgs`: Flags to pass to `makeWrapper`, added to executable calling the generated `.js` with `node` as an interpreter. These scripts are defined in `package.json`.
* `nodejs`: The `nodejs` package to build against, using the corresponding `npm` shipped with that version of `node`. Defaults to `pkgs.nodejs`.
* `npmDeps`: The dependencies used to build the npm package. Especially useful to not have to recompute workspace dependencies.

#### prefetch-npm-deps {#javascript-buildNpmPackage-prefetch-npm-deps}

`prefetch-npm-deps` is a Nixpkgs package that calculates the hash of the dependencies of an npm project ahead of time.

```console
$ ls
package.json package-lock.json index.js
$ prefetch-npm-deps package-lock.json
...
sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=
```

#### fetchNpmDeps {#javascript-buildNpmPackage-fetchNpmDeps}

`fetchNpmDeps` is a Nix function that requires the following mandatory arguments:

- `src`: A directory / tarball with `package-lock.json` file
- `hash`: The output hash of the node dependencies defined in `package-lock.json`.

It returns a derivation with all `package-lock.json` dependencies downloaded into `$out/`, usable as an npm cache.

#### importNpmLock {#javascript-buildNpmPackage-importNpmLock}

This function replaces the npm dependency references in `package.json` and `package-lock.json` with paths to the Nix store.
How each dependency is fetched can be customized with the `fetcherOpts` argument.

This is a simpler and more convenient alternative to [`fetchNpmDeps`](#javascript-buildNpmPackage-fetchNpmDeps) for managing npm dependencies in Nixpkgs.
There is no need to specify a `hash`, since it relies entirely on the integrity hashes already present in the `package-lock.json` file.

##### Inputs {#javascript-buildNpmPackage-inputs}

- `npmRoot`: Path to package directory containing the source tree.
  If this is omitted, the `package` and `packageLock` arguments must be specified instead.
- `package`: Parsed contents of `package.json`
- `packageLock`: Parsed contents of `package-lock.json`
- `pname`: Package name
- `version`: Package version
- `fetcherOpts`: An attribute set of arguments forwarded to the underlying fetcher.

It returns a derivation with a patched `package.json` & `package-lock.json` with all dependencies resolved to Nix store paths.

:::{.note}
`npmHooks.npmConfigHook` cannot be used with `importNpmLock`.
Use `importNpmLock.npmConfigHook` instead.
:::

:::{.example}

##### `pkgs.importNpmLock` usage example {#javascript-buildNpmPackage-example}
```nix
{ buildNpmPackage, importNpmLock }:

buildNpmPackage {
  pname = "hello";
  version = "0.1.0";
  src = ./.;

  npmDeps = importNpmLock {
    npmRoot = ./.;
  };

  npmConfigHook = importNpmLock.npmConfigHook;
}
```
:::

:::{.example}
##### `pkgs.importNpmLock` usage example with `fetcherOpts` {#javascript-buildNpmPackage-example-fetcherOpts}