npm equivalent of yarn resolutions?

Question

Is there an npm equivalent of the yarn resolutions functionality? There is no mention of it in the npm package.json docs.

For example, I want to install [email protected] and one of its dependencies (@lerna/publish) at 3.3.2 as well. Currently doing that with yarn like so, but would prefer to use npm and not manually change package-lock.json or anything dodgy like that.

"devDependencies": {
  "lerna": "3.3.2",
},
"resolutions": {
  "@lerna/publish": "3.3.2"
}

Answer 1

This does not seem to be supported by npm natively, however this package aims to add this functionality:

https://github.com/rogeriochaves/npm-force-resolutions

Answer 2

npm is due to support overrides, which is equivalent to yarn's resolutions.

For more information about the current RFC status:

https://github.com/npm/rfcs/blob/latest/accepted/0036-overrides.md

Answer 3

As far as I can tell, npm-force-resolutions does not work with npm v7. The package-lock.json format changed in v7 and npm-force-resolutions no longer updates the relevant fields.

However, it is relatively easy to write a script to restrict your dependency tree to only 1 version of a package, e.g.

#!/usr/bin/env node

/* eslint-disable unicorn/prevent-abbreviations */
/* eslint-disable import/unambiguous */
/* eslint-disable import/no-commonjs */
/* eslint-disable node/shebang */

const fs = require('fs').promises;
const path = require('path');

const main = async (resolutions) => {
  const packageLockFilePath = path.resolve(__dirname, '../package-lock.json');

  for (const [name, version] of Object.entries(resolutions)) {
    const packageLock = JSON.parse(await fs.readFile(packageLockFilePath));

    const packagePaths = Object.keys(packageLock.packages);

    const deletePaths = [];

    for (const packagePath of packagePaths) {
      if (packagePath.endsWith('/' + name)) {
        if (packageLock.packages[packagePath].version !== version) {
          deletePaths.push(packagePath);
        }
      }
    }

    for (const packagePath of deletePaths) {
      for (const deletePath of deletePaths) {
        if (packagePath === deletePath || packagePath.startsWith(deletePath + '/')) {
          // eslint-disable-next-line fp/no-delete
          delete packageLock.packages[packagePath];
        }
      }
    }

    await fs.writeFile(
      packageLockFilePath,
      JSON.stringify(packageLock, null, '  '),
    );
  }
};

main(require('../package.json').resolutions);

This script simply removes all links to dependencies that do not satisfy resolutions defined in package.json.

To execute the script, just add it to package.json scripts and define resolutions field, e.g.

{
  "scripts": {
    "postinstall": "node bin/fix-package-lock.js"
  },
  "resolutions": {
    "webpack": "5.6.0"
  }
}

resolutions is simply a map of package names and the exact versions of those packages that should be kept in the dependency tree, i.e. the above configuration will remove all versions of webpack that are not 5.6.0. As long you install [email protected] version as a dependency of the project you are working with, this will guarantee that all packages load the same version of webpack.

Answer 4

Npm equivalent to yarn resolutions is overrides. After the RFC was accepted now there's an epic to watch the progress of implementation. https://github.com/npm/statusboard/issues/343