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

A absolute right method, check target is a real html element primary code:

    (function (scope) {
        if (!scope.window) {//May not run in window scope
            return;
        }
        var HTMLElement = window.HTMLElement || window.Element|| function() {};

        var tempDiv = document.createElement("div");
        var isChildOf = function(target, parent) {

            if (!target) {
                return false;
            }
            if (parent == null) {
                parent = document.body;
            }
            if (target === parent) {
                return true;
            }
            var newParent = target.parentNode || target.parentElement;
            if (!newParent) {
                return false;
            }
            return isChildOf(newParent, parent);
        }
        /**
         * The dom helper
         */
        var Dom = {
            /**
             * Detect if target element is child element of parent
             * @param {} target The target html node
             * @param {} parent The the parent to check
             * @returns {} 
             */
            IsChildOf: function (target, parent) {
                return isChildOf(target, parent);
            },
            /**
             * Detect target is html element
             * @param {} target The target to check
             * @returns {} True if target is html node
             */
            IsHtmlElement: function (target) {
                if (!X.Dom.IsHtmlNode(target)) {
                    return false;
                }
                return target.nodeType === 1;
            },
            /**
             * Detect target is html node
             * @param {} target The target to check
             * @returns {} True if target is html node
             */
            IsHtmlNode:function(target) {
                if (target instanceof HTMLElement) {
                    return true;
                }
                if (target != null) {
                    if (isChildOf(target, document.documentElement)) {
                        return true;
                    }
                    try {
                        tempDiv.appendChild(target.cloneNode(false));
                        if (tempDiv.childNodes.length > 0) {
                            tempDiv.innerHTML = "";
                            return true;
                        }
                    } catch (e) {

                    }
                }
                return false;
            }
        };
        X.Dom = Dom;
    })(this);

Answer 2

(element instanceof $ && element.get(0) instanceof Element) || element instanceof Element

This will check for even if it is a jQuery or JavaScript DOM element

Answer 3

The using the root detection found here, we can determine whether e.g. alert is a member of the object's root, which is then likely to be a window:

function isInAnyDOM(o) { 
  return (o !== null) && !!(o.ownerDocument && (o.ownerDocument.defaultView || o.ownerDocument.parentWindow).alert); // true|false
}

To determine whether the object is the current window is even simpler:

function isInCurrentDOM(o) { 
  return (o !== null) && !!o.ownerDocument && (window === (o.ownerDocument.defaultView || o.ownerDocument.parentWindow)); // true|false
}

This seems to be less expensive than the try/catch solution in the opening thread.

Don P

Answer 4

Test if obj inherits from Node.

if (obj instanceof Node){
    // obj is a DOM Object
}

Node is a basic Interface from which HTMLElement and Text inherit.

Answer 5

No need for hacks, you can just ask if an element is an instance of the DOM Element:

const isDOM = el => el instanceof Element

Answer 6

Not to hammer on this or anything but for ES5-compliant browsers why not just:

function isDOM(e) {
  return (/HTML(?:.*)Element/).test(Object.prototype.toString.call(e).slice(8, -1));
}

Won't work on TextNodes and not sure about Shadow DOM or DocumentFragments etc. but will work on almost all HTML tag elements.