实现instanceof操作符

实现instanceof操作符

const theInstanceof = function (object, constructor) {
  if (typeof object !== 'object' || typeof constructor !== 'function') {
    return false
  }
  let proto = Object.getPrototypeOf(object)
  while (proto) {
    const prototype = constructor.prototype
    if (proto === prototype) return true
    proto = Object.getPrototypeOf(proto)
  }
  return false
}

/********************* test *********************/

function Foo () {
}

const foo1 = new Foo()
const anyObj = {}

console.log(theInstanceof(foo1, Foo))
console.log(theInstanceof(anyObj, Foo))