parcel-bundler/src/utils/localRequire.js

Blazing fast, zero configuration web application bundler

const {dirname} = require('path');
const promisify = require('../utils/promisify');
const resolve = promisify(require('resolve'));
const installPackage = require('./installPackage');

const cache = new Map();

async function localRequire(name, path, triedInstall = false) {
  let [resolved] = await localResolve(name, path, triedInstall);
  return require(resolved);
}

async function localResolve(name, path, triedInstall = false) {
  let basedir = dirname(path);
  let key = basedir + ':' + name;
  let resolved = cache.get(key);
  if (!resolved) {
    try {
      resolved = await resolve(name, {basedir});
    } catch (e) {
      if (e.code === 'MODULE_NOT_FOUND' && !triedInstall) {
        await installPackage(name, path);
        return await localResolve(name, path, true);
      }
      throw e;
    }
    cache.set(key, resolved);
  }

  return resolved;
}

localRequire.resolve = localResolve;
module.exports = localRequire;