WIP: Support Yarn Global

[tunnckoCore]

• blocked by Support for Yarn global jonschlinkert/global-modules#8
• stay tuned to Proposal for adding postinstall step that sets ENV variables yarnpkg/yarn#5806

[tunnckoCore]

There is jonschlinkert/global-modules#8 (comment) by Jon.

[tunnckoCore]

Consider using global-dirs

Demo

import globalDirs from 'global-dirs';

function isInstalledGlobally(name) {
  /* eslint-disable no-restricted-syntax */

  let exists = false;
  for (const [, dirs] of Object.entries(globalDirs)) {
    for (const [, globalPath] of Object.entries(dirs)) {
      const fp = path.join(globalPath, name);
      if (fs.existsSync(fp)) {
        exists = true;
        break;
      }
    }
  }
  return exists;
}