var browser = {
  foo: () => console.log('foo'),
}

class OurBrowser {
  answer = 42
  constructor() {
    return new Proxy(this, {
      get: function(obj, prop) {
        if (typeof browser[prop] === 'function') {
          return function(...args) {
            console.log(`browser.${prop}(${args}) called`)
            return browser[prop](...args)
          }
        } else {
          return obj[prop]
        }
      }
    })
  }
}
const ob = new OurBrowser()
console.log(ob.answer)
console.log(ob.answer2)
ob.foo()

function foo() {
  console.log('foo')
  return 42
}
function bar() {
  console.log('foo() was called')
  return foo()
}
console.log(bar())

foo() was called
foo
42

foo
foo() was called
42