4. If the package's name doesn't match any of the executables it provides, add an entry in [pkgs/development/node-packages/main-programs.nix](https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/node-packages/main-programs.nix). This will be the case for all scoped packages, e.g., `@angular/cli`.
5. Add and commit all modified and generated files.

For more information about the generation process, consult the [README.md](https://github.com/svanderburg/node2nix) file of the `node2nix` tool.

To update npm packages in nixpkgs, run the same `generate.sh` script:

```sh
./pkgs/development/node-packages/generate.sh
```

#### Git protocol error {#javascript-git-error}

Some packages may have Git dependencies from GitHub specified with `git://`.
GitHub has [disabled unencrypted Git connections](https://github.blog/2021-09-01-improving-git-protocol-security-github/#no-more-unauthenticated-git), so you may see the following error when running the generate script:

```
The unauthenticated git protocol on port 9418 is no longer supported
```

Use the following Git configuration to resolve the issue:

```sh
git config --global url."https://github.com/".insteadOf git://github.com/
```

## Tool specific instructions {#javascript-tool-specific}

### buildNpmPackage {#javascript-buildNpmPackage}

`buildNpmPackage` allows you to package npm-based projects in Nixpkgs without the use of an auto-generated dependencies file (as used in [node2nix](#javascript-node2nix)).
It works by utilizing npm's cache functionality -- creating a reproducible cache that contains the dependencies of a project, and pointing npm to it.

Here's an example:

```nix
{
  lib,
  buildNpmPackage,
  fetchFromGitHub,
}:

buildNpmPackage (finalAttrs: {
  pname = "flood";
  version = "4.7.0";

  src = fetchFromGitHub {
    owner = "jesec";
    repo = "flood";
    tag = "v${finalAttrs.version}";
    hash = "sha256-BR+ZGkBBfd0dSQqAvujsbgsEPFYw/ThrylxUbOksYxM=";
  };

  npmDepsHash = "sha256-tuEfyePwlOy2/mOPdXbqJskO6IowvAP4DWg8xSZwbJw=";

  # The prepack script runs the build script, which we'd rather do in the build phase.
  npmPackFlags = [ "--ignore-scripts" ];

  NODE_OPTIONS = "--openssl-legacy-provider";

  meta = {
    description = "Modern web UI for various torrent clients with a Node.js backend and React frontend";
    homepage = "https://flood.js.org";
    license = lib.licenses.gpl3Only;
    maintainers = with lib.maintainers; [ winter ];
  };
})
```

In the default `installPhase` set by `buildNpmPackage`, it uses `npm pack --json --dry-run` to decide what files to install in `$out/lib/node_modules/$name/`, where `$name` is the `name` string defined in the package's `package.json`.
Additionally, the `bin` and `man` keys in the source's `package.json` are used to decide what binaries and manpages are supposed to be installed.
If these are not defined, `npm pack` may miss some files, and no binaries will be produced.

#### Arguments {#javascript-buildNpmPackage-arguments}

* `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}`.