get-global-context.js

function getGlobalThis() {
  if (typeof globalThis !== 'undefined') return globalThis
  if (typeof global !== 'undefined') return global
  if (typeof self !== 'undefined') return self /* eslint-disable-line no-restricted-globals */
  if (typeof window !== 'undefined') return window
  if (typeof this !== 'undefined') return this
  return {} // should never happen
}

shorter-context.js

const globalContext = 
  (typeof self === 'object' && self.self === self && self) ||
  (typeof global === 'object' && global.global === global && global) || 
  this