npm-install-size/lib/fetch.js

Check the install size of any NPM package before installing it.

import fetch from 'node-fetch';
import tar from 'tar';
import fs from 'fs/promises';

export async function retry(fn, retries = 3, delay = 500) {
  let lastErr;
  for (let i = 0; i < retries; i++) {
    try {
      return await fn();
    } catch (err) {
      lastErr = err;
      if (i < retries - 1) await new Promise(res => setTimeout(res, delay));
    }
  }
  throw lastErr;
}

export function parsePkgArg(arg) {
  // Handles scoped packages and version, e.g. @babel/core@7.0.0
  const match = arg.match(/^(@[^/]+\/[^@]+|[^@]+)(?:@(.*))?$/);
  if (!match) return { name: arg, version: undefined };
  return { name: match[1], version: match[2] };
}

export async function getLatestTarballUrl(pkgArg) {
  const { name, version } = parsePkgArg(pkgArg);
  const encoded = encodeURIComponent(name);
  const url = `https://registry.npmjs.org/${encoded}`;
  const res = await retry(() => fetch(url));
  if (!res.ok) throw new Error(`Package not found`);
  const data = await res.json();
  let ver = version || data['dist-tags']?.latest;
  if (!ver || !data.versions[ver]) throw new Error(`Version not found`);
  return { tarball: data.versions[ver].dist.tarball, version: ver };
}

export async function downloadAndExtractTarball(tarballUrl, destDir) {
  const res = await retry(() => fetch(tarballUrl));
  if (!res.ok) throw new Error(`Failed to download tarball`);
  await fs.mkdir(destDir, { recursive: true });
  return new Promise((resolve, reject) => {
    const extractStream = tar.x({ cwd: destDir, strip: 1 });
    res.body.pipe(extractStream);
    res.body.on('error', reject);
    extractStream.on('finish', resolve);
    extractStream.on('error', reject);
  });
}

export async function fetchPackageVersions(pkgName) {
  const encoded = encodeURIComponent(pkgName);
  const url = `https://registry.npmjs.org/${encoded}`;
  const res = await retry(() => fetch(url));
  if (!res.ok) throw new Error(`Package not found`);
  const data = await res.json();
  return Object.keys(data.versions).sort((a, b) => {
    // Sort semver descending
    return b.localeCompare(a, undefined, { numeric: true, sensitivity: 'base' });
  });
}

export async function fetchPackageMeta(pkgArg) {
  const { name, version } = parsePkgArg(pkgArg);
  const encoded = encodeURIComponent(name);
  const url = `https://registry.npmjs.org/${encoded}`;
  const res = await retry(() => fetch(url));
  if (!res.ok) throw new Error(`Package not found`);
  const data = await res.json();
  if (version && data.versions[version]) {
    return data.versions[version];
  }
  return data;
}