lib.ts

declare const Zotero: any
declare const location: any

export const is7 = (typeof location !== 'undefined' && location.search) ? ((new URLSearchParams(location.search)).get('is7') === 'true') : Zotero.platformMajorVersion >= 102

function clientname(): string {
  if (typeof location !== 'undefined' && location.search) return (new URLSearchParams(location.search)).get('clientName')
  // if (process.versions.node) return 'Zotero' // testing
  if (Zotero.clientName) return Zotero.clientName as string
  if (Zotero.BetterBibTeX?.clientName) return Zotero.BetterBibTeX.clientName as string
  throw new Error('Unable to detect clientName')
}

export const clientName = clientname()
export const client = clientName.toLowerCase().replace('-', '')

main.ts

global.Zotero = {
  platformMajorVersion: 0,
  clientName: 'zotero',
}

import { clientName } from './lib'
console.log(clientName)