meteor/tools/cli/dev-bundle-helpers.js

import { pathJoin, getDevBundle, statOrNull } from '../fs/files';
import { installNpmModule } from '../isobuild/meteor-npm.js';

export async function ensureDependencies(deps) {
  const devBundleLib = pathJoin(getDevBundle(), 'lib');
  const devBundleNodeModules = pathJoin(devBundleLib, 'node_modules');

  // Check if each of the requested dependencies resolves, if not
  // mark them for installation.
  const needToInstall = Object.create(null);
  Object.keys(deps).forEach(dep => {
    const pkgDir = pathJoin(devBundleNodeModules, dep);
    const pkgStat = statOrNull(pkgDir);
    const alreadyInstalled = pkgStat && pkgStat.isDirectory();
    if (!alreadyInstalled) {
      const versionToInstall = deps[dep];
      needToInstall[dep] = versionToInstall;
    }
  });

  // Install each of the requested modules.
  for (const dep of Object.keys(needToInstall)) {
    await installNpmModule(dep, needToInstall[dep], devBundleLib);
  }
}