@semantic-release/npm/lib/prepare.js

semantic-release plugin to publish a npm package

const path = require('path');
const {move} = require('fs-extra');
const execa = require('execa');

module.exports = async ({tarballDir, pkgRoot}, {cwd, env, stdout, stderr, nextRelease: {version}, logger}) => {
  const basePath = pkgRoot ? path.resolve(cwd, pkgRoot) : cwd;

  logger.log('Write version %s to package.json in %s', version, basePath);

  const versionResult = execa('npm', ['version', version, '--no-git-tag-version'], {cwd: basePath, env});
  versionResult.stdout.pipe(
    stdout,
    {end: false}
  );
  versionResult.stderr.pipe(
    stderr,
    {end: false}
  );

  await versionResult;

  if (tarballDir) {
    logger.log('Creating npm package version %s', version);
    const packResult = execa('npm', ['pack', basePath], {cwd, env});
    packResult.stdout.pipe(
      stdout,
      {end: false}
    );
    packResult.stderr.pipe(
      stderr,
      {end: false}
    );

    const tarball = (await packResult).stdout.split('\n').pop();
    await move(path.resolve(cwd, tarball), path.resolve(cwd, tarballDir.trim(), tarball));
  }
};