How do you check if a JavaScript Object is a DOM Object?

Question

I\'m trying to get:

document.createElement(\'div\')  //=> true
{tagName: \'foobar something\'}  //=> false

In my own scripts, I used

Answer 1

According to mdn

Element is the most general base class from which all objects in a Document inherit. It only has methods and properties common to all kinds of elements.

We can implement isElement by prototype. Here is my advice:

/**
 * @description detect if obj is an element
 * @param {*} obj
 * @returns {Boolean}
 * @example
 * see below
 */
function isElement(obj) {
  if (typeof obj !== 'object') {
    return false
  }
  let prototypeStr, prototype
  do {
    prototype = Object.getPrototypeOf(obj)
    // to work in iframe
    prototypeStr = Object.prototype.toString.call(prototype)
    // '[object Document]' is used to detect document
    if (
      prototypeStr === '[object Element]' ||
      prototypeStr === '[object Document]'
    ) {
      return true
    }
    obj = prototype
    // null is the terminal of object
  } while (prototype !== null)
  return false
}
console.log(isElement(document)) // true
console.log(isElement(document.documentElement)) // true
console.log(isElement(document.body)) // true
console.log(isElement(document.getElementsByTagName('svg')[0])) // true or false, decided by whether there is svg element
console.log(isElement(document.getElementsByTagName('svg'))) // false
console.log(isElement(document.createDocumentFragment())) // false